host cell smooth endoplasmic reticulum

description: The irregular network of unit membranes, visible only by electron microscopy, that occurs in the host cell cytoplasm of many eukaryotic cells. The membranes form a complex meshwork of tubular channels, which are often expanded into slitlike cavities called cisternae. The host smooth ER has no ribosomes adhering to the outer surface.


host cell mitochondrial envelope

category: biolink:CellularComponent biolink:AnatomicalEntity biolink:PhysicalEssence biolink:OrganismalEntity biolink:SubjectOfInvestigation biolink:BiologicalEntity biolink:ThingWithTaxon biolink:NamedThing biolink:PhysicalEssenceOrOccurrent

description: The double lipid bilayer enclosing the host cell mitochondrion and separating its contents from the host cell cytoplasm; includes the intermembrane space.


symbiont-containing vacuole

description: Membrane-bounded vacuole within a host cell in which a symbiont organism resides. The vacuole membrane is derived from both the host and symbiont.


name: double membrane vesicle viral factory lumen

description: The volume surrounded by the inner membrane of a double membrane vesicle viral factory.


host cell cytoplasm part

description: Any constituent part of the host cell cytoplasm, all of the contents of a cell excluding the plasma membrane and nucleus, but including other subcellular structures. The host is defined as the larger of the organisms involved in a symbiotic interaction.


host cell viral nucleoid

description: The region of a host cell that contains the viral genome.


host thylakoid

description: A membranous cellular structure within the host cell that bears the photosynthetic pigments in plants, algae, and cyanobacteria. In cyanobacteria thylakoids are of various shapes and are attached to, or continuous with, the host plasma membrane. In eukaryotic host cells they are flattened, membrane-bounded disk-like structures located in the chloroplasts; in the chloroplasts of higher plants the thylakoids form dense stacks called grana. Isolated thylakoid preparations can carry out photosynthetic electron transport and the associated phosphorylation.


T=31/pseudo31 icosahedral capsid

description: The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=31 or pseudo T=31 symmetry.


T=27/pseudo27 icosahedral capsid

description: The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=27 or pseudo T=27 symmetry.


T=169 icosahedral viral capsid

description: The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=169 symmetry. T=169 icosahedral capsid is composed of 12 pentameric and 1680 hexameric capsomeres for a total of 10140 capsid proteins.


T=21/pseudo21 icosahedral capsid

description: The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=21 or pseudo T=21 symmetry.


T=28 icosahedral capsid

description: The protein coat that surrounds the infective nucleic acid in some virus particles where the subunits (capsomeres) are arranged to form an icosahedron with T=28 symmetry.


postsynaptic specialization membrane

description: The membrane component of the postsynaptic specialization. This is the region of the postsynaptic membrane in which the population of neurotransmitter receptors involved in synaptic transmission are concentrated.


name: postsynaptic specialization membrane of symmetric synapse

description: The membrane component of the postsynaptic specialization of a symmetric synapse. This is the region of the postsynaptic membrane in which the population of neurotransmitter receptors involved in synaptic transmission are concentrated.


postsynaptic density membrane

description: The membrane component of the postsynaptic density. This is the region of the postsynaptic membrane in which the population of neurotransmitter receptors involved in synaptic transmission are concentrated.


nucleoid

description: The region of a virus, bacterial cell, mitochondrion or chloroplast to which the nucleic acid is confined.


type Ib terminal bouton

description: Terminal inflated portion of the axon of a glutamatergic neuron, containing the specialized apparatus necessary for the tonic release neurotransmitters that will induce the contraction of muscle. Type Ib terminal boutons are larger than type Is terminal boutons.


basal distal dendrite

description: Any dendrite in a dendritic tree that emerges near the basal pole of a neuron (e.g. in bipolar neurons, basal dendrites are either on the same side of the soma as the axon, or project toward the axon), and which is farthest away from the neuronal cell body (the soma).


cell wall-bounded periplasmic space

description: The region between the plasma membrane and the cell wall in organisms lacking an outer cell membrane such as yeast and Gram positive bacteria. The region is thinner than the equivalent in Gram negative bacteria.


name: monolayer-surrounded lipid storage body outer lipid monolayer

description: The single layer of phopholipids surrounding a lipid storage body.


left posteriolateral flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the left posteriolateral basal body and extends cytoplasmically toward the cell posterior, marking the left anterior boundary of the lateral shield and the left lateral region of the funis before exiting at the left lateral region of the cell body.


dendritic branch

description: A dendrite arising from another dendrite.


Golgi apparatus

description: A membrane-bound cytoplasmic organelle of the endomembrane system that further processes the core oligosaccharides (e.g. N-glycans) added to proteins in the endoplasmic reticulum and packages them into membrane-bound vesicles. The Golgi apparatus operates at the intersection of the secretory, lysosomal, and endocytic pathways.


postsynaptic Golgi apparatus

description: The network of the Golgi apparatus structures located within the postsynapse.


hyphal tip

description: The end, or tip, of a fungal hypha, where polarized growth occurs during hyphal elongation.


nucleolar chromatin

description: The portion of nuclear chromatin associated with the nucleolus; includes the DNA encoding the ribosomal RNA.


nucleolus-associated heterochromatin

description: Dense particles of heterochromatin, consisting of a loosely twisted strand about 600 Angstrom thick, found associated with the nucleolus.


nucleolus organizer region

description: A region of a chromosome where nucleoli form during interphase, and where genes encoding the largest rRNA precursor transcript are tandemly arrayed.


dendritic spine neck

description: Part of the dendritic spine that connects the dendritic shaft to the head of the dendritic spine.


S bouton

description: Synaptic bouton found in the ventral horn of the spinal cord. S boutons range in diameter from 0.5 to 8 um and contain spherical synaptic vesicles.


outer mucus layer

description: The outer of two mucus layers secreted by epithelial cells in the colon; the outer mucus layer is loosely packed and can be colonized by bacteria.


omegasome membrane

description: Any membrane that is part of an omegasome.


smooth endoplasmic reticulum cisterna

description: A subcompartment of the smooth endoplasmic reticulum consisting of lumenal expansion into a flattened, disc-shaped cavity.


subrhabdomeral cisterna

description: A membrane-bounded compartment that is found at the base of the rhabdomere and contains stored calcium, InsP3 receptors and smooth endoplasmic reticulum Ca2+-ATPase.


sub-surface cisterna

description: Specialization of the hypolemmal cisterna consisting of either single profiles or closely apposed stacks of endoplasmic reticulum in which the lumen is obliterated, lying 10-20 nm beneath the plasma membrane.


hypolemmal cisterna

description: Specialized part of the smooth endoplasmic reticulum that closely underlies the plasma membrane, usually within 60 nm or closer.


pseudopodium membrane

description: The portion of the plasma membrane surrounding a pseudopodium.


ciliary pocket

description: Invagination of the plasma membrane from which a cilium (also called flagellum) protrudes.


membrane microdomain

description: A membrane region with a lipid composition that is distinct from that of the membrane regions that surround it.


caveola neck

description: A membrane microdomain that forms a necklace around the bulb (crater) of a caveola. Intramembrane particles are concentrated in this region and cytoskeletal components, including actin, are highly enriched in the area underlying it.


eisosome membrane domain/MCC

description: A plasma membrane part that is composed of a furrow-like plasma membrane domain and associated integral transmembrane proteins.


dendritic spine membrane

description: The portion of the plasma membrane surrounding a dendritic spine.


host peribacteroid membrane

description: A host-derived membrane that surrounds one or more bacteroids (such as nitrogen-fixing bacteroids within legume root nodule cells).


transverse flagellum

description: A motile cilium found in dinoflagellates. It coils around the cell and provides the forward thrust for motility. It is often contained in a furrow called the cingulum, and emerges from a flagellar pore located in the cingulum.


sculpture element

description: The third layer of the sexine.


platelet glycocalyx

description: The carbohydrate rich layer at the outermost periphery of a platelet.


right tetrad

description: Set of four basal bodies found in Giardia species (trophozoite stage). It comprises the right lateral basal body pair and the right middle basal body pair (i.e. the anterior, ventral, caudal and posteriolateral basal bodies located to the left of the right nucleus of the trophozoite when viewed dorsally).


name: ventral disc supernumerary microtubule array

description: A partial left-handed spiral array of microtubules that lies generally dorsal to the main ventral disc microtubule array in Giardia species (trophozoite stage).


axonemal central pair

description: Part of the axoneme consisting of the inner two microtubule doublets of the 9+2 axoneme occurring in most motile cilia.


endocytic vesicle lumen

description: The volume enclosed by the membrane of an endocytic vesicle.


phagocytic vesicle lumen

description: The volume enclosed by the membrane of a phagocytic vesicle.


clathrin-coated endocytic vesicle lumen

description: The volume enclosed by the membrane of a clathrin-coated endocytic vesicle.


early phagosome lumen

description: The volume enclosed by the membrane of an early phagosome.


host apoplast

description: The apoplast region surrounding a host plant cell. Plants may be described as having two major compartments: the living symplast and the non-living apoplast. The apoplast is external to the plasma membrane and includes cell walls, intercellular spaces and the lumen of dead structures such as xylem vessels. Water and solutes pass freely through it. The host is defined as the larger of the organisms involved in a symbiotic interaction.


left ventral basal body

description: Any ciliary basal body that is part of a left ventral flagellum found in Giardia species (trophozoite stage).


organic molecular entity

Any molecular entity that contains carbon.


heteroorganic entity

A heteroorganic entity is an organic molecular entity in which carbon atoms or organic groups are bonded directly to one or more heteroatoms.


organochalcogen compound

An organochalcogen compound is a compound containing at least one carbon-chalcogen bond.


organooxygen compound

An organochalcogen compound containing at least one carbon-oxygen bond.


endospore-forming forespore

description: Portion of the cell formed during the process of bacterial sporulation that will ultimately become the core of the endospore. An endospore is a type of dormant cell that is resistant to adverse conditions.


inner layer of spore wall

description: Either of the two innermost layers of the spore wall, as described in Saccharomyces.


9+2 non-motile cilium

description: A non-motile cilium where the axoneme has a ring of nine outer microtubule doublets plus two central microtubules (and is therefore called a 9+2 axoneme).


kinocilium

description: A nonmotile primary cilium that is found at the apical surface of auditory receptor cells. The kinocilium is surrounded by actin-based stereocilia.


granum

description: Distinct stack of lamellae seen within chloroplasts. Grana contain the pigments, electron transfer compounds, and enzymes essential to the light-dependent reactions of photosynthesis.


internode region of axon

description: An axon part that is located between the nodes of Ranvier and surrounded by compact myelin sheath.


cleavage body

description: A nuclear body that contains proteins involved in pre-mRNA 3'-end cleavage and polyadenylation, such as DDX1, CSTF2 and CPSFs, as well as the transcription factors TFIIE and TFIIF. Cleavage bodies are localized adjacent to Cajal bodies and are involved in mRNA3'-end processing.


F bouton

description: Synaptic bouton found in the ventral horn of the spinal cord. F boutons range in diameter from 0.5 to 7 um and contain flattened or pleomorphic synaptic vesicles.


eisosome

description: A cell part that is composed of the eisosome membrane or MCC domain, a furrow-like plasma membrane sub-domain and associated integral transmembrane proteins, and the proteins (eisosome filaments) that form a scaffolding lattice on the cytoplasmic face. Eisosomes broadly affect overall plasma membrane organization.


description: Organized structure of distinctive morphology and function, not bounded by a lipid bilayer membrane and occurring outside the cell.


cellulosome

description: An extracellular multi-enzyme complex containing up to 11 different enzymes aligned on a non-catalytic scaffolding glycoprotein. Functions to hydrolyze cellulose.


mating projection base

description: The region where the mating projection meets the bulk of the cell, in unicellular fungi exposed to mating pheromone.


synaptic cleft

description: The narrow gap that separates the presynaptic and postsynaptic membranes, into which neurotransmitter is released.


apoplast

description: The cell membranes and intracellular regions in a plant are connected through plasmodesmata, and plants may be described as having two major compartments: the living symplast and the non-living apoplast. The apoplast is external to the plasma membrane and includes cell walls, intercellular spaces and the lumen of dead structures such as xylem vessels. Water and solutes pass freely through it.


perivitelline space

description: The space between the membrane of an oocyte and a surrounding membranous structure (zona pellucida or perivitelline membrane).


lysosomal lumen

description: The volume enclosed within the lysosomal membrane.


endolysosome lumen

description: The volume enclosed by the membrane of an endolysosome. An endolysosome is a transient hybrid organelle formed by fusion of a late endosome with a lysosome.


cytolytic granule

description: A specialized secretory lysosome that is present in cells with cytolytic capability such as cytotoxic T lymphocytes and natural killer cells. Cytolytic granules mediate the storage and regulated excretion of lytic molecules for killing of target cells.


porous cell septum

description: A septum or cross wall which does not entirely span the space between two portions of cell wall and may contain a specialized central pore structure. A porous septum allows the movement of organelles and/or cytoplasm between compartments.


dolipore septum

description: A septum, or cross-wall, between two portions of a cell or hypha; contains a central pore around which the septum is swollen to form a barrel-shaped structure; pore is covered on each side of the septum by a septal pore cap (parenthosome).


host cell synapse

description: The junction between a nerve fiber of one host neuron and another host neuron or muscle fiber or glial cell; the site of interneuronal communication.


cellular bud neck septin structure

description: Any of a series of septin structures that are localized in the bud neck of a budding fungal cell during the cell cycle.


annular furrow extracellular matrix

description: The extracellular matrix part that is a regularly spaced indentation in the outer cortical layer of the cuticle. The pattern of annular furrows corresponds to sites of invaginations in hypodermal cell membranes that, in turn, correspond to submembranous regions where actin microfilament bundles assemble early in lethargus, the first phase of the molting cycle in which activity and feeding decline.


yolk granule

description: Discrete structures that partition the water-insoluble portion of the yolk of oocytes and ova, which may or may not be membrane enclosed.


name: symbiont-containing vacuolar membrane network

description: Tubular network of extensions from the symbiont-containing vacuole membrane that protrude into the host cytoplasm.


cis-Golgi network membrane

description: The lipid bilayer surrounding any of the compartments that make up the cis-Golgi network.


pellicle

description: The structure enclosing certain parasite cells such as certain apicomplexa and Euglenozoa; consists of the cell membrane with its associated infrastructure of microtubules, microfilaments and other organelles.


spine apparatus

description: A specialization of the endomembrane system found in some classes of dendritic spines consisting of two or more closely apposed lamellae with interspersed electron dense material. The endomembrane component is continuous with the smooth endoplasmic reticulum.


dendritic tuft

description: The terminal specialization found in some types of dendrites which consists of numerous small terminal branches, giving the dendrite a tufted appearance.


peribacteroid fluid

description: The soluble material inside the peribacteroid membrane, but outside of the bacteroid, within a bacteroid-containing symbiosome.


spindle matrix

description: A proteinaceous, nuclear-derived structure that embeds the microtubule spindle apparatus from pole to pole in a microtubule-independent manner during mitosis.


climbing fiber

description: The axon of inferior olive neuron that projects to the cerebellar cortex, largely via the inferior cerebellar peduncle. They range in diameter from 1-3 um and are myelinated until they enter the granule cell layer. They give off collaterals to the deep cerebellar nuclei. They synapse extensively with the dendrites of Purkinje cells in the molecular layer, where each fiber branches repeatedly to climb along the Purkinje cell dendritic tree. Each Purkinje cell is innervated by only a single climbing fiber.


spine synapse

description: A type of synapse occurring between an axon and a dendritic spine.


brush border

description: The dense covering of microvilli on the apical surface of an epithelial cell in tissues such as the intestine, kidney, and choroid plexus; the microvilli aid absorption by increasing the surface area of the cell.


cellular bud scar

description: Crater-like ring of chitinous scar tissue located on the surface of the mother cell. It is formed after the newly emerged daughter cell separates thereby marking the site of cytokinesis and septation. The number of bud scars that accumulate on the surface of a cell is a useful determinant of replicative age.


exopher

description: An extracellular vesicle that is approximately four microns in diameter, released by budding out of cells into the extracellular space, and hypothesized to be a mechanism for disposal of unwanted cellular material including protein aggregates and damaged organelles.


female germline ring canal outer rim

description: An electron opaque backbone of the insect ovarian ring canal that is a part of or adjacent to the plasma membrane. The outer rim is established as the cleavage furrow is arrested, and contains F-actin, anillin, glycoproteins and at least one a protein with a high content of phosphorylated tyrosine residues.


free sarcoplasmic reticulum membrane

description: The part of the sarcoplasmic reticulum membrane that contains calcium pumps and is devoted to calcium uptake. The free sarcoplasmic reticulum membrane consists of the longitudinal sarcoplasmic reticulum membrane and the non-junctional region of the terminal cisterna membrane.


filiform apparatus

description: A complex of cell wall invaginations in a synergid cell, similar to those in transfer cells.


endospore core

description: An intracellular part that represents the innermost portion of an endospore; the endospore core is dehydrated, enriched in dipicolinic acid and divalent cations, and metabolically inactive.


phagocytic cup lip

description: The tip or margin of the progressing circular lamella that engulfs a particle during phagocytosis. When the two lips of the cup fuse it is converted into a phagosome.


chlorosome envelope

description: The structure, composed of a monolayer of glycolipids with embedded proteins, that encloses the pigments and other contents of the chlorosome.


organelle-enclosing lipid monolayer

description: A lipid monolayer that surrounds and encloses an organelle.


microneme

description: A small, elongated secretory organelle that forms part of the apical complex, located along the main axis of an apicomplexan parasite cell within the extreme apical region and at the periphery under the inner membrane complex. Of the specialized secretory compartments identified in apicomplexans, micronemes discharge their contents first, during initial contact of the parasite's apical pole with the host cell surface. Micronemal proteins function during parasite attachment and penetration into the target cell.


mitochondrial crista

description: Any of the inward folds of the mitochondrial inner membrane. Their number, extent, and shape differ in mitochondria from different tissues and organisms. They appear to be devices for increasing the surface area of the mitochondrial inner membrane, where the enzymes of electron transport and oxidative phosphorylation are found. Their shape can vary with the respiratory state of the mitochondria.


magnetosome

description: A membrane-bound organelle that envelops particles of magnetic iron minerals in magnetotactic bacteria. Magnetosomes form linear chains that align along the cellular motility axis at midcell and function in bacterial navigation along the Earth's magnetic field. They are formed by invagination of the cell inner membrane; in some species they remain connected to the inner membrane, in others they pinch off to form independent intracellular vesicles.


dinoflagellate epicone

description: The part of a dinoflagellate cell above the cingulum; also referred to as the anterior portion of a dinoflagellate cell. It is separated from the hypocone by the cingulum.


p-block molecular entity

A main group molecular entity that contains one or more atoms of a p-block element.


chalcogen molecular entity

Any p-block molecular entity containing a chalcogen.


etioplast stroma

description: The space enclosed by the double membrane of an etioplast but excluding the prothylakoid space. It contains the etioplast DNA.


mating projection

description: The projection formed by unicellular fungi in response to mating pheromone.


central element

description: A structural unit of the synaptonemal complex found between the lateral elements.


ascus epiplasm

description: Ascus cytoplasm that is not packaged into ascospores.


phragmosome

description: A flattened membranous vesicle containing cell wall components.


eyespot apparatus

description: A small pigmented organelle used in single-celled organisms to detect light.


C zone

description: A region of the A band in which myosin-binding protein C is located and that can be seen by electron microscopy. This is a functional zone that also includes myosin.


Gemini of coiled bodies

description: Nuclear bodies frequently found near or associated with Cajal bodies (also called coiled bodies or CBs). Gemini of coiled bodies, or 'gems', are similar in size and shape to CBs, and often indistinguishable under the microscope. Unlike CBs, gems do not contain small nuclear ribonucleoproteins (snRNPs); they contain a protein called survivor of motor neurons (SMN) whose function relates to snRNP biogenesis. Gems are believed to assist CBs in snRNP biogenesis, and to play a role in the etiology of spinal muscular atrophy (SMA).


nuclear body

description: Extra-nucleolar nuclear domains usually visualized by confocal microscopy and fluorescent antibodies to specific proteins.


LYSP100-associated nuclear domain

description: A nuclear body that is enriched in the lymphoid cell-specific protein LYSp100B; LANDs are globular, electron-dense structures and are morphologically distinct from the annular structures characteristic of PML bodies.


omega speckle

description: A nucleoplasmic speckle distributed in the interchromatin space of cells in close proximity to chromatin. Omega speckles are distinct from interchromatin granules and contain heterogeneous nuclear RNA-binding proteins (hnRNPs).


paraspeckles

description: Discrete subnuclear bodies in the interchromatin nucleoplasmic space, often located adjacent to nuclear specks. 10-20 paraspeckles are typically found in human cell nuclei.


nuclear speck

description: A discrete extra-nucleolar subnuclear domain, 20-50 in number, in which splicing factors are seen to be localized by immunofluorescence microscopy.


nuclear dicing body

description: A small round nuclear body, measuring 0.2-0.8 microns in diameter that is diffusely distributed throughout the nucleoplasm. Several proteins known to be involved in miRNA processing have been localized to these structures. D-bodies are thought to be involved in primary-miRNA processing and/or storage/assembly of miRNA processing complexes.


interchromatin granule

description: A class of nuclear body measuring 20-25 nm in diameter and distributed throughout the interchromatin space, linked together by thin fibrils. They are believed to be storage centers for various snRNAs, snRNPs, serine/arginine-rich proteins and RNA polymerase II. A typical mammalian cell contains 25-50 clusters of interchromatin granules. Interchromatin granule clusters do not contain the heterogeneous nuclear RNA-binding proteins (hnRNPs).


sphere organelle

description: A nuclear body that is found in the germinal vesicles of amphibian oocytes, and consist of three major parts: a remarkably spherical body about 5-10 pm in diameter, smaller spherical or nearly spherical granules on the surface, and inclusions of various sizes that strongly resemble the surface granules. The parts of the sphere organelle have distinct compositions, including splicing snRNAs and proteins.


Cajal body

description: A class of nuclear body, first seen after silver staining by Ramon y Cajal in 1903, enriched in small nuclear ribonucleoproteins, and certain general RNA polymerase II transcription factors; ultrastructurally, they appear as a tangle of coiled, electron-dense threads roughly 0.5 micrometers in diameter; involved in aspects of snRNP biogenesis; the protein coilin serves as a marker for Cajal bodies. Some argue that Cajal bodies are the sites for preassembly of transcriptosomes, unitary particles involved in transcription and processing of RNA.


nuclear exosome focus

description: An nuclear body involved in nuclear mRNA surveilllance. Contains at least Mmi1, or an ortholog of it, and the nuclear exosome.


pseudopodium

description: A temporary protrusion or retractile process of a cell, associated with flowing movements of the protoplasm, and serving for locomotion and feeding.


axonemal A tubule inner sheath

description: A structural network of microtubule inner proteins (MIPs) located inside the lumen of the A tubule of the axonemal microtubule doublet that helps stabilize the A tubule.


dense fibrillar component

description: A structure found in the nucleolus, which contains newly synthesized preribosomal RNA (pre-rRNA) and a collection of proteins.


cell body fiber

description: A neuron projection that is found in unipolar neurons and corresponds to the region between the cell body and the point at which the single projection branches.


chromoplast stroma

description: The space enclosed by the double membrane of a chromoplast but excluding the photosynthetic material.


apicolateral plasma membrane

description: The apical end of the lateral plasma membrane of epithelial cells.


Golgi apparatus subcompartment

description: A compartment that consists of a lumen and an enclosing membrane, and is part of the Golgi apparatus.


Golgi trans cisterna

description: The Golgi cisterna farthest from the endoplasmic reticulum; the final processing compartment through which proteins pass before exiting the Golgi apparatus; the compartment in which N-linked protein glycosylation is completed.


Golgi cisterna

description: Any of the thin, flattened membrane-bounded compartments that form the central portion of the Golgi complex.


Golgi stack

description: The set of thin, flattened membrane-bounded compartments, called cisternae, that form the central portion of the Golgi complex. The stack usually comprises cis, medial, and trans cisternae; the cis- and trans-Golgi networks are not considered part of the stack.


apical proximal dendrite

description: The dendrite of the dendritic tree, which emerges near the apical pole of a neuron, and which is the closest to the cell body of the neuron (the soma).


right anterior flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It originates at the right anterior basal body, extends laterally through the cytoplasm, crosses the left anterior axoneme, and exits as a membrane-bound flagellum on the anterior right side of the cell.


germline ring canal

description: Germline specific intercellular bridge. During cyst formation in insects, ring canals interconnect the cells of the cyst, facilitating the passage of cytoplasmic components between cells.


female germline ring canal

description: An intercellular bridge that connects the germline cells of a female cyst.


male germline ring canal

description: An intercellular bridge that connects the germline cells of a male cyst.


mitochondrial envelope

description: The double lipid bilayer enclosing the mitochondrion and separating its contents from the cell cytoplasm; includes the intermembrane space.


vestibular calyx terminal

description: The giant, cup-shaped axon terminal of a vestibular afferent neuron, serving as a post-synaptic contact to a type I hair cell.


neuron projection terminus

description: The specialized, terminal region of a neuron projection such as an axon or a dendrite.


calyx of Held

description: The terminal specialization of a calyciferous axon which forms large synapses in the mammalian auditory central nervous system.


axon terminus

description: Terminal inflated portion of the axon, containing the specialized apparatus necessary to release neurotransmitters. The axon terminus is considered to be the whole region of thickening and the terminal button is a specialized region of it.


cone cell pedicle

description: A specialized axon terminus which is produced by retinal cone cells. Pedicles are large, conical, flat end-feet (8-10 micrometers diameter) of the retinal cone axon that lie more or less side by side on the same plane at the outer edge of the outer plexiform layer (OPL).


Herring body

description: The dilated terminal portions of neurosecretory axons constituting the hypothalamohypophyseal tract, found in close proximity to sinusoidal capillaries in the posterior pituitary. Herring bodies consist of aggregates of membrane-bound neurosecretory vesicles where oxytocin or antidiuretic hormone (ADH) are stored prior to release. Each Herring body also contains ATP and either neurophysin I or neurophysin II which bind to oxytocin and ADH, respectively.


nuclear envelope lumen

description: The region between the two lipid bilayers of the nuclear envelope; 20-40 nm wide.


P2 peroxisome

description: A subform of peroxisome that corresponds to an intermediate in a peroxisome assembly pathway, which operates by conversion of peroxisomal subforms in the direction P1, P2 -> P3 -> P4 -> P5 -> P6. P2 peroxisomes are distinguished from the other subforms on the bases of buoyant density and protein content; they are the least dense of the subforms observed.


oral apparatus

description: Complex basket- or funnel-like structure used by the cell to collect food and channel it to the cytostome; includes specialized sub-structures made up of closely-spaced cilia and underlying basal bodies and fibrillar systems.


uropod membrane

description: The portion of the plasma membrane surrounding a uropod.


cell trailing edge membrane

description: The portion of the plasma membrane surrounding the trailing edge of a motile cell.


procentriole

description: A cellular structure that is the site of a developing centriole, which will become a microtubule organizing center. During the canonical pathway of centriole duplication that occurs during the cell division cycle, procentrioles grow at the proximal ends of both mother and daughter centrioles. In the newly divided cells, the original mother and daughter centrioles become mother centrioles while the procentrioles become the new daughter centrioles. Procentrioles can also arise from de novo pathways that occur in multiciliated cells. In ciliated epithelial cells, numerous procentrioles arise form electron dense material referred to as fibrous granules and deuterosomes. The pathway of procentriole formation in multiciliated protists appears to be similar to that in mammalian multiciliated epithelium. In sperm of primitive land plants, multiple procentrioles are formed from a blepharoplast giving rise to multicilated sperm cells.


storage vacuole

description: A vacuole that functions primarily in the storage of materials, including nutrients, pigments, waste products, and small molecules.


reservosome

description: A large membrane-bound endocytic organelle present only in members of the Schizotrypanum subgenus of the Trypanosoma genus and is defined as the site of storage of endocytosed macromolecules and lysosomal enzymes. It is found at the posterior end of epimastigote forms of Trypanosoma cruzi, but absent in amastigotes and trypomastigotes.


terminal cisterna

description: The portion of sarcoplasmic reticulum devoted to calcium ion storage and calcium ion release.


stigma papilla

description: A plant cell papilla that is part of a stigma papilla cell.


apical lamina of hyaline layer

description: A fibrous network that is part of the hyalin layer extracellular matrix. The apical lamina is thought to be principally composed of the glycoproteins fibropellins. This matrix has been found in echinoderms.


reservosome membrane

description: The lipid bilayer surrounding a reservosome.


left ventral flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the left ventral basal body and exits the cell body proximally and dorsal to the ventral disc.


plasma membrane bounded cell projection

description: A prolongation or process extending from a cell and that is bounded by plasma membrane, e.g. a cilium, lamellipodium, or axon.


9+0 non-motile cilium

description: A non-motile cilium where the axoneme has a ring of nine outer microtubule doublets but no central microtubules (and is therefore called a 9+0 axoneme).


microspike

description: A dynamic, actin-rich projection extending from the surface of a migrating animal cell.


growth cone lamellipodium

description: A thin sheetlike process extended by the leading edge of an axonal or dendritic growth cone; contains a dense meshwork of actin filaments.


basal dendrite

description: A dendrite that emerges near the basal pole of a neuron. In bipolar neurons, basal dendrites are either on the same side of the soma as the axon, or project toward the axon.


C-fiber

description: The axon of a dorsal root ganglion cell that are responsive to pain and temperature. C-fibers are small in diameter (0.2-1.5 um) and unmyelinated.


distal dendrite

description: The dendrite of the dendritic tree that is farthest away from the neuronal cell body (the soma).


proximal dendrite

description: The dendrite of the dendritic tree that is closest to the neuronal cell body (the soma).


dendritic tree

description: The entire complement of dendrites for a neuron, consisting of each primary dendrite and all its branches.


rod spherule

description: A specialized neuron projection which is the site of synaptic transmission produced by retinal rod cells. Rod spherules are small round enlargements of the axon (3-5 micrometers diameter) or even extensions of the cell body.


right posteriolateral flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the right posteriolateral basal body and extends cytoplasmically toward the cell posterior, marking the right anterior boundary of the lateral shield and the right lateral region of the funis before exiting at the right lateral region of the cell body.


hippocampal mossy fiber

description: An axon of a hippocampal granule cell, including dentate gyrus granule cell and CA3 granule cell, characterized by expansions (mossy fiber expansions) giving the fibers a mossy appearance. These unmyelinated axons were first described by Ramon y Cajal.


CA3 pyramidal cell dendrite

description: A dendrite of a hippocampal CA3 pyramidal cell.


axonal spine

description: A spine that originates from the axon, usually from the initial segment.


giant axon

description: Extremely large, unmyelinated axon found in invertebrates. Has high conduction speeds and is usually involved in panic or escape responses.


cilium

description: A specialized eukaryotic organelle that consists of a filiform extrusion of the cell surface and of some cytoplasmic parts. Each cilium is largely bounded by an extrusion of the cytoplasmic (plasma) membrane, and contains a regular longitudinal array of microtubules, anchored to a basal body.


filopodium

description: Thin, stiff, actin-based protrusion extended by the leading edge of a motile cell such as a crawling fibroblast or amoeba, or an axonal or dendritic growth cone, or a dendritic shaft.


dendritic cell dendrite

description: A branched cellular projection (or cytoplasmic extension) that is extended from the surface of a dendritic immune cell, and which enables the cell to sample luminal pathogens and increase the surface area for antigen presentation to T cells.


rod telodendria

description: Rod telodendria are projections that originate from the rod pedicle and form gap junctions with other photoreceptors within the outer plexiform layer of the retina.


growth cone filopodium

description: A thin, stiff protrusion extended by the leading edge of an axonal or dendritic growth cone.


accessory outer segment

description: A cilium-like cell projection emanating from the inner segment and running alongside the outer segment of photoreceptors.


9+0 motile cilium

description: A motile cilium where the axoneme has a ring of nine outer microtubule doublets but no central microtubules (and is therefore called a 9+0 axoneme).


9+2 motile cilium

description: A motile cilium where the axoneme has a ring of nine outer microtubule doublets plus two central microtubules (and is therefore called a 9+2 axoneme).


non-motile cilium

description: A cilium which may have a variable array of axonemal microtubules but does not contain molecular motors.


cone telodendria

description: Cone telodendria are projections that originate from the cone pedicle and form gap junctions with other photoreceptors within the outer plexiform layer of the retina.


muscle cell projection

description: A prolongation or process extending from a muscle cell. A muscle cell is a mature contractile cell, commonly known as a myocyte. This cell has as part of its cytoplasm myofibrils organized in various patterns.


cytoneme

description: A long, thin, polarized cell projection that contains actin and can extend for distances many times the diameter of the cell. Cytonemes represent extensions of cell cytoplasm and typically have a diameter of approximately 0.2um.


right ventral flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the right ventral basal body and exits the cell body proximally and dorsal to the ventral disc.


pollen tube

description: A tubular cell projection that is part of a pollen tube cell and extends from a pollen grain.


macropinocytic cup

description: A cell projection that forms at the site of macropinocytosis, a form of endocytosis that results in the uptake of relatively large amounts of extracellular fluid. The macropinocytic cup membrane selectively excludes certain proteins, such as H36 or PM4C4 in Dictyostelium, and the underlying cytoskeleton is enriched in F-actin and coronin.


right caudal flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the right caudal basal body, extending cytoplasmically and exiting at the posterior end of the cell body.


primary dendrite

description: A dendrite emerging from the cell body (the soma) of a neuron.


parallel fiber

description: A parallel fiber results from the bifurcation of a cerebellar granule cell axon in the molecular layer into two diametrically opposed branches, that are oriented parallel to the long axis of the folium.


neuron spine

description: A small membranous protrusion, often ending in a bulbous head and attached to the neuron by a narrow stalk or neck.


left anterior flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It originates at the left anterior basal body, extends laterally through the cytoplasm, crosses the right anterior axoneme, and exits as a membrane-bound flagellum on the anterior left side of the cell.


cerebellar mossy fiber

description: An axon arising from cerebellar projecting cells in the cochlea, vestibular nuclei, spinal cord, reticular formation, cerebellar nuclei and basilar pontine nuclei. Mossy fibers enter through all three cerebellar peduncles and send collaterals to the deep cerebellar nuclei, then branch in the white matter and terminate in the granule cell layer. Through this branching, a given mossy fiber can innervate several folia. Mossy fibers synapse on granule cells. The synaptic contacts are made at enlargements along the length of the mossy fiber called mossy fiber rosettes. The enlargements of the rosettes give the axons a mossy-looking appearance in Golgi stained preparations.


gemmule

description: Spine-like process found on some neurons, e.g., periglomerular cells of olfactory cortex.


photoreceptor cell cilium

description: A specialised 9+0 non-motile cilium found in photoreceptor cells. A ciliary transition zone called 'photoreceptor connecting cilium' links the photoreceptor outer segment to the inner segment.


motile cilium

description: A cilium which may have a variable arrangement of axonemal microtubules and also contains molecular motors. It may beat with a whip-like pattern that promotes cell motility or transport of fluids and other cells across a cell surface, such as on epithelial cells that line the lumenal ducts of various tissues; or they may display a distinct twirling motion that directs fluid flow asymmetrically across the cellular surface to affect asymmetric body plan organization. Motile cilia can be found in single as well as multiple copies per cell.


proximal neuron projection

description: The portion of an axon or dendrite that is close to the neuronal cell body.


actin-based cell projection

description: A cell projection supported by an assembly of actin filaments, and which lacks microtubules.


podocyte primary projection

description: A cell projection originating from a renal glomerular podocyte and extending to the renal glomerular podocyte foot.


rhabdomere microvillus

description: Thin cylindrical membrane-covered projection on the surface of a rhabdomere.


left caudal flagellum

description: A cilium (also called flagellum) found in Giardia species (trophozoite stage). It is nucleated by the left caudal basal body, extending cytoplasmically and exiting at the posterior end of the cell body.


podocyte foot

description: A cell projection of a podocyte (glomerular visceral epithelial cell) forming a foot-like structure projecting from a podocyte primary projection, that wraps around capillaries of a renal glomerulus. Adjacent feet (pedicels) interdigitate, leaving thin filtration slits between them, which are covered by slit diaphragms.


uropod

description: A membrane projection with related cytoskeletal components at the trailing edge of a cell in the process of migrating or being activated, found on the opposite side of the cell from the leading edge or immunological synapse, respectively.


cell hair

description: A long, thin cell projection that contains F-actin and tubulin, with microtubules centrally located and F-actin peripherally located.


longitudinal flagellum

description: A motile cilium found in dinoflagellates. It trails the cell and acts as a steering rudder. It is often partially contained in a furrow called the sulcus, and emerges from a flagellar pore located in the sulcus.


telodendria

description: Telodendria are projections that originate from the axon pedicle and form gap junctions with other neurons.


apical distal dendrite

description: Any dendrite in a dendritic tree that emerges near the apical pole of a neuron, and which is farthest away from the neuronal cell body (the soma).


dentate gyrus mossy fiber

description: Hippocampal mossy fiber produced by dentate gyrus granule cells.


sperm flagellum

description: A microtubule-based flagellum (or cilium) that is part of a sperm, a mature male germ cell that develops from a spermatid.


dendritic filopodium

description: A small, membranous protrusion found primarily on dendritic stretches of developing neurons. May receive synaptic input, and can develop into dendritic spines.


basal proximal dendrite

description: Any dendrite in a dendritic tree that emerges near the basal pole of a neuron (e.g. in bipolar neurons, basal dendrites are either on the same side of the soma as the axon, or project toward the axon), and which is the closest to the cell body of the neuron (the soma).


rhabdomere

description: The specialized microvilli-containing organelle on the apical surfaces of a photoreceptor cell containing the visual pigment rhodopsin and most of the proteins involved in phototransduction.


dinoflagellate peduncle

description: A small, flexible, finger-like projection of cytoplasm containing an array of microtubles and located near the flagellar pores in some photosynthetic as well as nonphotosynthetic dinoflagellate species. Its functions are not fully understood, but it has been associated with feeding behavior (phagotrophy).


apical dendrite

description: A dendrite that emerges near the apical pole of a neuron. In bipolar neurons, apical dendrites are located on the opposite side of the soma from the axon.


plastid

description: Any member of a family of organelles found in the cytoplasm of plants and some protists, which are membrane-bounded and contain DNA. Plant plastids develop from a common type, the proplastid.


phenyloplast

description: A chloroplast-derived plastid in which the solid form of phenol is stored.


apicoplast

description: The plastid organelle found in apicomplexans.


etioplast

description: A plastid arrested in the development of chloroplasts from proplastids due to absence of light or low light conditions.


leucoplast

description: A colorless plastid involved in the synthesis of monoterpenes.


chromoplast

description: A plastid containing pigments other than chlorophyll, usually yellow and orange carotenoid pigments.


proteinoplast

description: A leucoplast in which protein is stored.


cyanelle

description: A plastid that contains unstacked, phycobilisome-bearing thylakoid membranes and is surrounded by a double membrane with a peptidoglycan layer in the intermembrane space between the two envelope membranes. Cyanelles are characteristic of algae in the class Glaucophyta, and may represent an ancestral form of plastid.


cell plate

description: The nascent cell membrane and cell wall structure that forms between two daughter nuclei near the center of a dividing plant cell. It develops at the equatorial region of the phragmoplast. It grows outwards to join with the lateral walls and form two daughter cells.


myelin sheath

description: An electrically insulating fatty layer that surrounds the axons of many neurons. It is an outgrowth of glial cells: Schwann cells supply the myelin for peripheral neurons while oligodendrocytes supply it to those of the central nervous system.


egg chorion

description: A protective, noncellular membrane that surrounds the eggs of various animals including insects and fish.


primary lysosome

description: A lysosome before it has fused with a vesicle or vacuole.


ascospore-type prospore nucleus

description: Any nucleus that is part of a ascospore-type prospore.


coated membrane

description: A single or double lipid bilayer with any of several different proteinaceous coats that can associate with membranes. Membrane coats include those formed by clathrin plus an adaptor complex, the COPI and COPII complexes.


bacterial-type flagellum filament

description: The long (approximately 20 nm), thin external structure of the bacterial-type flagellum, which acts as a propeller.


dendritic spine origin

description: The part of the dendritic spine neck where the spine arises from the dendritic shaft.


non-membrane-bounded organelle

description: Organized structure of distinctive morphology and function, not bounded by a lipid bilayer membrane. Includes ribosomes, the cytoskeleton and chromosomes.


archaeal-type flagellum

description: A non-membrane-bounded organelle superficially similar to a bacterial-type flagellum; they both consist of filaments extending outside the cell, and rotate to propel the cell, but the archaeal flagella (also called archaella) have a unique structure which lacks a central channel. Similar to bacterial type IV pilins, the archaeal flagellins (archaellins) are made with class 3 signal peptides and they are processed by a type IV prepilin peptidase-like enzyme. The archaellins are typically modified by the addition of N-linked glycans which are necessary for proper assembly and/or function.


cellular anatomical entity

description: A part of a cellular organism that is either an immaterial entity or a material entity with granularity above the level of a protein complex but below that of an anatomical system. Or, a substance produced by a cellular organism with granularity above the level of a protein complex.


ventral disc overlap zone

description: A region of the ventral disc of Giardia species (trophozoite stage) where two portions of the same array of microtubules overlap (the microtubule array makes a complete circle and overlaps on itself).


intercellular bridge

description: A direct connection between the cytoplasm of two cells that is formed following the completion of cleavage furrow ingression during cell division. They are usually present only briefly prior to completion of cytokinesis. However, in some cases, such as the bridges between germ cells during their development, they become stabilised.


pollen tube tip

description: The region at growing end of the pollen tube cell, where polarized growth occurs.


microvillus membrane

description: The portion of the plasma membrane surrounding a microvillus.


somatodendritic compartment

description: The region of a neuron that includes the cell body (cell soma) and dendrite(s), but excludes the axon.


endoplasmic reticulum lumen

description: The volume enclosed by the membranes of the endoplasmic reticulum.


extrachromosomal rDNA circle

description: Circular DNA molecules encoding ribosomal RNA that are replicated independently of chromosomal replication. These molecules originate in the chromosome but are excised and circularized, often by intramolecular homologous recombination between direct tandem repeats.


axonemal basal plate

description: Part of the axoneme consisting of a highly electron-dense region at the distal end of the ciliary transition zone within the axonemal lumen at which the axonemal central pair of microtubules is connected to the rest of the axonemal structure.


medial membrane band

description: A sterol-rich region of the plasma membrane which forms at the cell surface overlying the contractile ring and spreads into the invaginating plasma membrane surrounding the septum.


vacuolar lumen

description: The volume enclosed within the vacuolar membrane.


somatic portion of tanycyte

description: Portion of a tanycyte that lies within the ependyma and contains the nucleus. A tanycyte is a specialized elongated ventricular ependymal cell that has processes that extend to the outer, or pial, surface of the CNS.


sarcomere

description: The repeating unit of a myofibril in a muscle cell, composed of an array of overlapping thick and thin filaments between two adjacent Z discs.


perinuclear region of cytoplasm

description: Cytoplasm situated near, or occurring around, the nucleus.


subsynaptic reticulum

description: An elaborate tubulolamellar membrane system that underlies the postsynaptic cell membrane.


plant cell papilla

description: A cell projection that is a short, rounded projection from a plant epidermal cell.


tail portion of tanycyte

description: Elongated process of a tanycyte, devoid of cytoplasmic extensions, that courses through the hypothalamic nuclei to form small endfoot processes that terminate either on blood vessels or at the pial surface of the brain. A tanycyte is a specialized elongated ventricular ependymal cell.


name: axonemal microtubule doublet outer junction

description: The structure which joins the B1 protofilament of the B tubule to the A10 and A11 protofilaments of the A tubule within an axonemal microtubule doublet.


bacterial-type flagellum basal body

description: One of the three major substructures of the bacterial-type flagellum, the basal body is embedded in the cell envelope (the plasma membrane, peptidoglycan cell wall, and, if one is present, the outer membrane); it houses the secretion apparatus that exports the more distal components and the flagellar motor.


yeast-form cell wall

description: The wall surrounding a cell of a dimorphic fungus growing in the single-cell budding yeast form, in contrast to the filamentous or hyphal form.


nucleoplasm

description: That part of the nuclear content other than the chromosomes or the nucleolus.


cell body

description: The portion of a cell bearing surface projections such as axons, dendrites, cilia, or flagella that includes the nucleus, but excludes all cell projections.


manchette

description: A tubular array of microtubules that extends from the perinuclear ring surrounding the spermatid nucleus to the flagellar axoneme. The manchette may also contain F-actin filaments.


contractile actin filament bundle

description: An actin filament bundle in which the filaments are loosely packed (approximately 30-60 nm apart) and arranged with opposing polarities; the loose packing allows myosin (usually myosin-II) to enter the bundle.


extrahaustorial membrane

description: The membrane surrounding the symbiont haustorium during symbiosis, derived from the host plasma membrane.


mitochondrial inner membrane

description: The inner, i.e. lumen-facing, lipid bilayer of the mitochondrial envelope. It is highly folded to form cristae.


ectexine

description: The outer part of the exine, which stains positively with basic fuchsin in optical microscopy and has higher electron density in conventionally prepared TEM sections.


periphagosomal region of cytoplasm

description: Cytoplasm situated near, or occurring around, a phagosome.


actin body

description: An amorphous cytoskeletal structure consisting of aggregated actin filaments and associated proteins (including fibrin and capping protein) in which there is little or no actin filament turnover. In yeast (S. pombe and S. cerevisiae) these are found only in quiescent cells and are thought to serve as a reserve store of actin.


Z disc

description: Platelike region of a muscle sarcomere to which the plus ends of actin filaments are attached.


karyomere

description: A membrane-bound intermediate cleavage-stage structure of individual or groups of chromosomes that coalesces and fuses with other karyomeres to form a nucleus during interphase. Karyomere formation occurs in blastomeres undergoing rapid cell division.


actin tubule

description: A cellular structure, approximately 13 nm in diameter, consisting of three actin filaments bundled together.


megasporocyte nucleus

description: The nucleus of a megasporocyte, a diploid cell that undergoes meiosis to produce four megaspores, and its descendents.


old cell pole

description: The cell pole distal from the most recent cell division.


sperm fibrous sheath

description: A cytoskeletal structure surrounding the axoneme and outer dense fibers of the sperm flagellum. Consists of two longitudinal columns connected by closely arrayed semicircular ribs that assemble from distal to proximal throughout spermiogenesis. The fibrous sheath probably influences the degree of flexibility, plane of flagellar motion, and the shape of the flagellar beat.


pathogen-containing vacuole membrane

description: Host-derived membrane of a pathogen-containing vacuole.


bacterial-type flagellum hook

description: The portion of the bacterial-type flagellum that connects the filament to the basal body.


new cell pole

description: The cell pole proximal to the most recent cell division.


thylakoid lumen

description: The volume enclosed by a thylakoid membrane.


A band

description: The dark-staining region of a sarcomere, in which myosin thick filaments are present; the center is traversed by the paler H zone, which in turn contains the M line.


name: mitotic actomyosin contractile ring, intermediate layer

description: The region of the mitotic actomyosin ring in between the proximal layer and the actin filament layer. This region contains the accessory protein network, some actin filaments and connections between the proximal layer and the actin filament layer.


actin filament bundle

description: An assembly of actin filaments that are on the same axis but may be oriented with the same or opposite polarities and may be packed with different levels of tightness.


hemicellulose network

description: Network composed of hemicelluloses; members of a class of plant cell wall polysaccharide that cannot be extracted from the wall by hot water or chelating agents, but can be extracted by aqueous alkali. Includes xylan, glucuronoxylan, arabinoxylan, arabinogalactan II, glucomannan, xyloglucan and galactomannan.


description: A membrane-bounded flattened sac that is formed during micropexophagy between the membrane tips of an engulfing vacuole, completing the engulfment and sequestration of peroxisomes from the cytosol, and forming a micropexophagic body within the lumen of the vacuole.


generative cell nucleus

description: The nucleus of the generative cell, a cell contained within the pollen grain that will divide to produce two haploid sperm cells.


cis-Golgi network

description: The network of interconnected tubular and cisternal structures located at the convex side of the Golgi apparatus, which abuts the endoplasmic reticulum.


P6 peroxisome

description: A subform of peroxisome that corresponds to an intermediate in a peroxisome assembly pathway, which operates by conversion of peroxisomal subforms in the direction P1, P2 -> P3 -> P4 -> P5 -> P6. P6 peroxisomes are distinguished from the other subforms on the bases of buoyant density and protein content, and are equivalent to mature peroxisomes.


name: microtubule organizing center attachment site

description: A region of the nuclear envelope to which a microtubule organizing center (MTOC) attaches; protein complexes embedded in the nuclear envelope mediate direct or indirect linkages between the microtubule cytoskeleton and the nuclear envelope.


axoneme

description: The bundle of microtubules and associated proteins that forms the core of cilia (also called flagella) in eukaryotic cells and is responsible for their movements.


perinuclear endoplasmic reticulum lumen

description: The volume enclosed by the membranes of the perinuclear endoplasmic reticulum.


polyadic synapse

description: A synapse consisting of a single presynapse and multiple postsynapses. These postsynapses may come from the same cell of from different cells. Polyadic synapses are common in arthropod and nematode central nervous systems.


mating projection membrane

description: The portion of the plasma membrane surrounding a mating projection, the projection formed by unicellular fungi in response to mating pheromone.


methane-oxidizing organelle

description: A cytoplasmic, membrane-bounded compartment found within Methanotrophic bacteria that contains enzymes and electron transfer proteins for methane catabolism. This structure is analogous to the thylakoid of Cyanobacteria and the anammoxosome of anaerobic ammonium oxidation organisms.


cleavage apparatus septin structure

description: Any of a series of structures composed of septins and septin-associated proteins localized to the cleavage plane which are involved in cytokinesis.


rod photoreceptor outer segment

description: The outer segment of a vertebrate rod photoreceptor that contains sealed membrane discs that are not connected to the ciliary membrane and containing rhodopsin photoreceptor proteins.


name: lytic vacuole within protein storage vacuole

description: A membrane-bounded compartment containing crystals of phytic acid and proteins characteristic of a lytic vacuole, found within a storage vacuole.


ciliary cap

description: An intracellular compartmentalized cilium structure found in insect spermatids which is bounded by a membrane derived from the invagination of the cell membrane that remains associated with the primary cilium as it is internalized. The ciliary cap is maintained at the end of the axoneme distal to the centriole and is separated from the cytosolic axoneme/cytoplasm by a putative transition zone, which may extend into the ciliary cap, and include a structure at the base of the ciliary cap termed the ring centriole.


female germline ring canal inner rim

description: A proteinaceous actin-rich layer of the insect ovarian ring canal that forms subcortically to the outer rim. The electron dense inner rim accumulates after the final mitotic division of each germline syncytia, and contains actin, a phosphotyrosine protein, and a number of cytoskeletal proteins.


name: cortical layer of collagen and cuticulin-based cuticle extracellular matrix

description: The cuticle layer that lies directly beneath the lipid-containing epicuticle. The cortical layer contains collagens and insoluble, non-collagenous cuticulins and is characterized by a distinct annular pattern consisting of regularly spaced annular ridges delineated by annular furrows. An example of this component is found in Caenorhabditis elegans.


ascospore-type prospore

description: An immature spore undergoing development. The spore usually consists of nucleic acid, prospore membrane(s) that encase the nucleic acid, and ultimately a cell wall that covers the membrane(s). This type of spore is observed in ascospore-forming fungi.


phagocytic cup

description: An invagination of the cell membrane formed by an actin dependent process during phagocytosis. Following internalization it is converted into a phagosome.


male germ cell nucleus

description: The nucleus of a male germ cell, a reproductive cell in males.


exosporium

description: The outermost layer of a bacterial endospore, which is loosely attached and located outside of the endospore coat. It is generally composed of protein, carbohydrate, and perhaps lipid.


mitotic actomyosin contractile ring

description: A cytoskeletal structure composed of actin filaments, myosin, and myosin-associated proteins that forms beneath the plasma membrane of many cells, including animal cells and yeast cells, in a plane perpendicular to the axis of the mitotic spindle, i.e. the cell division plane. Ring contraction is associated with centripetal growth of the membrane that divides the cytoplasm of the two future daughter cells. In animal cells, the mitotic contractile ring is located inside the plasma membrane at the location of the cleavage furrow. In budding fungal cells, e.g. mitotic S. cerevisiae cells, the mitotic contractile ring forms beneath the plasma membrane at the mother-bud neck before mitosis.


multiple synapse bouton

description: A single axon terminal bouton making contact onto two or more dendritic spines protruding either from a single dendrite or from multiple dendrites.


cellular bud membrane

description: The portion of the plasma membrane surrounding a cellular bud.


intracellular organelle lumen

description: An organelle lumen that is part of an intracellular organelle.


microbody lumen

description: The volume enclosed by the membranes of a microbody.


photoreceptor outer segment

description: The outer segment of a vertebrate photoreceptor that contains a stack of membrane discs embedded with photoreceptor proteins.


extracellular core region of desmosome

description: The desmosomal part containing the desmosomal cadherins, desmogleins and desmocollins, that establish contact and adhere to neighboring cells in a Ca2+-dependent manner.


amyloplast starch grain

description: Plant storage body for amylose and amylopectin, 1-100um in diameter, and located in amyloplasts. Also contains small amounts of enzymes, amino acids, lipids and nucleic acids. The shape of the grain varies widely amongst species, but is often spherical or disk-shaped.


plastid intermembrane space

description: The region between the inner and outer lipid bilayers of the plastid envelope.


mating projection tip membrane

description: The portion of the plasma membrane surrounding a mating projection tip.


asymmetric synapse

description: A type of synapse occurring between an axon and a dendritic spine or dendritic shaft. Asymmetric synapses, the most abundant synapse type in the central nervous system, involve axons that contain predominantly spherical vesicles and contain a thickened postsynaptic density. Most or all synapses of this type are excitatory.


name: mitotic spindle pole body attachment site

description: A region of the nuclear envelope to which a spindle pole body (SPB) attaches; protein complexes embedded in the nuclear envelope mediate direct or indirect linkages between the microtubule cytoskeleton and the nuclear envelope.


rhabdomere microvillus membrane

description: The portion of the plasma membrane surrounding a microvillus of a rhabdomere.


spore inner membrane

description: The membrane surrounding the spore core (endospore core) that separates it from its external environment.


cell wall

description: The rigid or semi-rigid envelope lying outside the cell membrane of plant, fungal, most prokaryotic cells and some protozoan parasites, maintaining their shape and protecting them from osmotic lysis. In plants it is made of cellulose and, often, lignin; in fungi it is composed largely of polysaccharides; in bacteria it is composed of peptidoglycan; in protozoan parasites such as Giardia species, it's made of carbohydrates and proteins.


mitochondrial inner boundary membrane

description: The portion of the mitochondrial inner membrane that is not invaginated to form cristae. The inner boundary membrane lies parallel to the outer membrane.


nuclear replication fork

description: The Y-shaped region of a nuclear replicating DNA molecule, resulting from the separation of the DNA strands and in which the synthesis of new strands takes place. Also includes associated protein complexes.


macropinocytic cup cytoskeleton

description: The part of the cortical actin cytoskeleton that forms part of a macropinocytic cup.


name: bacterial-type flagellum basal body, MS ring

description: One of the rings of the bacterial-type flagellar basal body; a double-flanged ring that anchors the basal body to the cytoplasmic membrane.


multivesicular body lumen

description: The volume enclosed by the outermost membrane of a multivesicular body.


pilus

description: A proteinaceous hair-like appendage on the surface of bacteria ranging from 2-8 nm in diameter.


pairing center

description: A special chromosome region located towards one end of a chromosome that contains dispersed copies of short, repetitive DNA sequences and functions as a cis-acting element essential for presynaptic homologous chromosome pairing and chromosome-nuclear envelope attachment.


nucleomorph

description: A small, vestigial nucleus found in some plastids that derive from a eukaryotic endosymbiont. Observed in chlorarachniophytes and cryptomonads, which acquired their plastids from a green and red alga respectively.


Gram-positive-bacterium-type cell wall

description: A layer of peptidoglycan found outside of the cytoplasmic membrane. The peptidoglycan is relatively thick (20-80nm) and retains the primary stain of the Gram procedure, thus cells appear blue after Gram stain. The cell walls often contain teichoic acids (acidic anionic polysaccharides) bound to the peptidoglycan. Examples of this component are found in Gram-positive bacteria.


microsporocyte nucleus

description: The nucleus of the microsporocyte. The microsporocyte is a diploid cell in which meiosis will occur, resulting in four microspores. A microspore is a spore that, in vascular plants, gives rise to a male gametophyte.


division septum

description: A cell septum which forms as part of the division site and functions in the compartmentalization of a cell into two daughter cells at division. A division septum spans a cell and does not allow exchange of organelles or cytoplasm between compartments.


ensheathing process

description: A cell projection (often from glial cells such as Schwann cells) that surrounds an unmyelinated axon or cell soma.


proximal portion of axoneme

description: The portion of the axoneme that is close to the base of the cilium.


female germ cell nucleus

description: The nucleus of the female germ cell, a reproductive cell in females.


microbody

description: Cytoplasmic organelles, spherical or oval in shape, that are bounded by a single membrane and contain oxidative enzymes, especially those utilizing hydrogen peroxide (H2O2).


bacterial outer membrane vesicle

description: A spherical, bilayered proteolipid vesicle released from gram-negative bacterial outer membranes.


type I terminal bouton

description: Terminal inflated portion of the axon of a glutamatergic neuron, containing the specialized apparatus necessary to release neurotransmitters that will induce the contraction of muscle. The axon terminus is considered to be the whole region of thickening and the terminal bouton is a specialized region of it.


photoreceptor connecting cilium

description: The portion of the photoreceptor cell cilium linking the photoreceptor inner and outer segments. It's considered to be equivalent to the ciliary transition zone.


nuclear matrix

description: The dense fibrillar network lying on the inner side of the nuclear membrane.


name: multiple synapse bouton, contacting multiple dendrites

description: A single axon terminal bouton making contact onto two or more dendritic spines protruding from multiple dendrites.


contractile ring

description: A cytoskeletal structure composed of filamentous protein that forms beneath the membrane of many cells or organelles, in the plane of cell or organelle division. Ring contraction is associated with centripetal growth of the membrane that divides the cytoplasm of the two daughter cells or organelles.


host cell membrane pore complex

description: Any small opening in a host cell membrane that allows the passage of gases and/or liquids, composed of host proteins.


migrasome

description: A vesicular organelle that forms on retraction fibers behind migrating cells and mediates the release of cytoplasmic contents during cell migration.


mitotic nuclear bridge midzone

description: The central region of a mitotic nuclear bridge, distal to the main portions of the daughter nuclei.


pellicular membrane

description: The portion of the plasma membrane surrounding the pellicle, a structure enclosing some parasite cells such as certain apicomplexa and Euglenozoa. These membranes are associated with an infrastructure of microtubules, microfilaments, and other organelles.


myofilament

description: Any of the smallest contractile units of a myofibril (striated muscle fiber).


leading edge of lamellipodium

description: That part of the lamellipodium which represents the distal part of the structure.


polytene chromosome ectopic fiber

description: A thread-like connection joining two regions of ectopically paired polytene chromosomes.


photoreceptor distal connecting cilium

description: The distal region of the photoreceptor connecting cilium is structurally unique to the photoreceptor and is maintained by retina-specific protein, SPATA7, and its interacting partners RPGR and RPGRIP1. It is essential for photoreceptor sensory cilium stability.


ficolin-1-rich granule lumen

description: Any membrane-enclosed lumen that is part of a ficolin-1-rich granule.


tertiary granule lumen

description: Any membrane-enclosed lumen that is part of a tertiary granule.


right ventral basal body

description: Any ciliary basal body that is part of a right ventral flagellum found in Giardia species (trophozoite stage).


microneme membrane

description: The lipid bilayer surrounding a microneme.


vesicle membrane

description: The lipid bilayer surrounding any membrane-bounded vesicle in the cell.


phragmoplast

description: The phragmoplast is a plant cell specific cytoplasmic structure composed of cytoskeletal polymers, membranes, and associated cytosolic proteins that functions as the focused secretory module for assembling the cell plate.


new growing cell tip

description: A cell tip that was newly formed at the last cell division, and that has started to grow after the cell has activated bipolar cell growth (i.e. in which new end take-off, NETO, has taken place). New end take-off is when monopolar cells initiate bipolar growth.


chloroplast inner membrane

description: The inner, i.e. lumen-facing, lipid bilayer of the chloroplast envelope; also faces the chloroplast stroma.


apical cytoplasm

description: The region of the cytoplasm located at the apical side of the cell. Used in reference to animal polarized epithelial cells.


axonemal central apparatus

description: Part of the 9+2 axoneme, that occurs in most motile cilia, consisting of the pair of two single central microtubules and their associated structures which include the central pair projections, the central pair bridges linking the two tubules, and the central pair caps which are attached to the distal or plus ends of the microtubules.


ventral surface of cell

description: The surface of a migrating cell that is in contact with the substratum or cell layer.


glycocalyx

description: A carbohydrate rich layer at the outermost periphery of a cell.


keratohyalin granule

description: A cytoplasmic, non-membrane bound granule of, at least, keratinocyte. Associated to keratin intermediate filaments and partially crosslinked to the cell envelope.


micronucleus

description: A membrane-bounded organelle of ciliated protozoan cells that contains a diploid copy of the cell's complete genome. Sections of contiguous sequence in the macronucleus are often interrupted by internal eliminated sequences (IES), and may be permuted, in micronuclei. Genic transcription is not found in micronuclei. Some ciliate species may contain multiple micronuclei per cell.


name: bacterial-type flagellum basal body, proximal rod

description: The portion of the central rod of the bacterial-type flagellar basal body that is proximal to the cell membrane; the proximal rod connects the distal rod to the flagellar motor.


plant-type cell wall

description: A more or less rigid structure lying outside the cell membrane of a cell and composed of cellulose and pectin and other organic and inorganic substances.


chrorion micropyle

description: A single cone-shaped specialization that forms an opening in the egg chorion that allows sperm entry into the egg prior to fertilization.


pirellulosome

description: A cytoplasmic structure found in bacterial phyla Planctomycetes and Verrucomicrobia containing a condensed nucleoid and ribosomes and surrounded by an intracytoplasmic membrane. It is surrounded by ribosome-free cytoplasm, in a compartment called the paryphoplasm.


dinoflagellate antapex

description: The anterior most point of a dinoflagellate hypocone.


postsynaptic membrane

description: A specialized area of membrane facing the presynaptic membrane on the tip of the nerve ending and separated from it by a minute cleft (the synaptic cleft). Neurotransmitters cross the synaptic cleft and transmit the signal to the postsynaptic membrane.


terminal cisterna lumen

description: The region between the inner and outer lipid bilayers of the terminal cisterna envelope. This space is enriched in calsequestrin.


stereocilium tip

description: A distinct compartment at the tip of a stereocilium, distal to the site of attachment to the apical cell surface. It consists of a dense matrix bridging the barbed ends of the stereocilium actin filaments with the overlying plasma membrane, is dynamic compared to the shaft, and is required for stereocilium elongation.


glycosome

description: A membrane-bounded organelle found in organisms from the order Kinetoplastida that houses the enzymes of glycolysis.


ruffle membrane

description: The portion of the plasma membrane surrounding a ruffle.


plasmodesmatal cytoplasmic sleeve

description: The space between the plasma membrane and the desmotubule of a plasmodesma.


concave side of sperm head

description: The concave part of the late spermatid head or spermatozoon head that forms the ventral portion of the head, particularly in some rodent species.


microsporidian-type endospore

description: The middle layer in a microsporidian spore wall that lies under the exospore and outside the plasma membrane, containing chitin and proteins.


actin wave

description: A cellular anatomical entity that is part of the actin cytoskeleton and results in a wave-like propagation of actin networks. It consists of dynamic structures traveling on the ventral (substrate-attached) side of the cell during cell migration, cytokinesis, adhesion and neurogenesis.


epididymosome

description: A microvesicle of the epididymal fluid, from which spermatozoa acquire membrane proteins.


perinucleolar compartment

description: The perinucleolar compartment (PNC) is a subnuclear structure associated with, but structurally distinct from, the nucleolus. The PNC contains large amounts of the heterogeneous nuclear ribonucleoprotein complex (hnRNP) called hnRNP 1 (PTB). Many RNA binding proteins as well as RNA polymerase III transcripts are highly enriched in this compartment. PTB and pol III transcripts are required for the integrity of the PNC.


type II terminal bouton

description: Terminal inflated portion of the axon of a non-glutamatergic neuron, containing the specialized apparatus necessary to release neurotransmitters at a regulatory synapse. The axon terminus is considered to be the whole region of thickening and the terminal bouton is a specialized region of it.


periarbuscular membrane

description: A host-derived membrane surrounding the symbiont arbuscule during symbiosis.


dinoflagellate apex

description: The anterior most point of a dinoflagellate epicone.


symbiont-containing vacuole membrane

description: The lipid bilayer surrounding a symbiont-containing vacuole, derived from both the host and symbiont.


ciliary microtubule quartet

description: A set of four specialized microtubules that originates from the basal bodies and wraps around the ciliary pocket membrane, likely supporting its distinct flask shape.


name: symmetric, GABA-ergic, inhibitory synapse

description: A neuron to neuron synapse that lacks an electron dense postsynaptic specialization, uses GABA as a neurotransmitter and whose activity results in inhibitory postsynaptic potentials.


scintillon

description: A body present in the cytoplasm of some dinoflagellates, which is the source of bioluminescence; emits light on acidification in the presence of oxygen.


Golgi membrane

description: The lipid bilayer surrounding any of the compartments of the Golgi apparatus.


cell pole

description: Either of two different areas at opposite ends of an axis of a cell.


P3 peroxisome

description: A subform of peroxisome that corresponds to an intermediate in a peroxisome assembly pathway, which operates by conversion of peroxisomal subforms in the direction P1, P2 -> P3 -> P4 -> P5 -> P6. P3 peroxisomes are formed by fusion of P1 and P2 peroxisomes, and are distinguished from the other subforms on the bases of buoyant density and protein content.


name: surface coat of collagen and cuticulin-based cuticle extracellular matrix

description: An electron dense, amorphous envelope that comprises the outermost layer of the cuticle. The surface coat is loosely apposed to the epicuticle, has distinct biochemical properties, is synthesized by cells other than the underlying hypodermis, and is labile. In addition to serving as a lubricant to protect against abrasion and dehydration, the surface coat may also play important roles in infection and immune evasion. An example of this component is found in Caenorhabditis elegans.


name: nuclear envelope adjacent to nuclear pore complex

description: The region of the nuclear envelope situated in close proximity to a nuclear pore complex.


rod photoreceptor disc lumen

description: The volume enclosed by the membrane of a rod photoreceptor cell disc membrane.


leaflet of membrane bilayer

description: Any of the two layers of lipid molecules that constitute a membrane.


distal portion of axoneme

description: The portion of the axoneme that is close to the tip of the cilium.


sperm mitochondrial sheath

description: The tightly packed helical sheath of ATP-producing mitochondria restricted to the midpiece of the sperm flagellum.


mucus layer

description: An extracellular region part that consists of a protective layer of mucus secreted by epithelial cells lining tubular organs of the body such as the colon or secreted into fluids such as saliva. Mucus is a viscous slimy secretion consisting of mucins (i.e. highly glycosylated mucin proteins) and various inorganic salts dissolved in water, with suspended epithelial cells and leukocytes.


name: extrinsic component of periplasmic side of cell outer membrane

description: The component of the cell outer membrane consisting of gene products and protein complexes that are loosely bound to periplasmic surface, but not integrated into the hydrophobic region.


nucleus leading edge

description: The area of a motile nucleus closest to the direction of movement.


dendritic knob

description: The terminal swelling of an apical dendrite of a ciliated olfactory receptor neuron. Each knob gives rise to 5 to 20 long delicate nonmotile cilia, which extend into the mucus covering the sensory epithelium.


pronucleus

description: The nucleus of either the ovum or the spermatozoon following fertilization. Thus, in the fertilized ovum, there are two pronuclei, one originating from the ovum, the other from the spermatozoon that brought about fertilization; they approach each other, but do not fuse until just before the first cleavage, when each pronucleus loses its membrane to release its contents.


rough endoplasmic reticulum lumen

description: The volume enclosed by the membranes of the rough endoplasmic reticulum.


perforation plate

description: A cell wall part that is the part of a wall of a vessel member and bears one or more openings (perforations).


pathogen-containing vacuole lumen

description: The enclosed volume within the sealed membrane of a pathogen-containing vacuole.


sperm glycocalyx

description: The carbohydrate rich layer at the outermost periphery of a sperm cell.


cuticular plate

description: A dense network of actin filaments found beneath the apical cell surface of hair cells, and into which stereocilia are inserted.


type I pilus

description: A short filamentous structure on the surface of a bacterial cell distinguished from other pili by their D-mannose-sensitive agglutinatination of erythrocytes. In E. coli, type I pili consist of a short tip fibrillum made up of the adhesin protein (FimH) and two minor subunits (FimG and FimF) that is joined to the pilus rod, a homopolymer of ~1000 FimA subunits.


amyloplast membrane

description: Either of the lipid bilayers that surround an amyloplast and form the amyloplast envelope.


polytene chromosome weak point

description: A region of the polytene chromosome where the diameter is considerably decreased, probably resulting from local differences in chromosome organization.


cyanelle stroma

description: The space enclosed by the double membrane of a cyanelle.


neuron projection branch point

description: The location where a secondary projection arises from a neuron projection.


chloroplast membrane

description: Either of the lipid bilayers that surround a chloroplast and form the chloroplast envelope.


cell body membrane

description: The plasma membrane of a cell that bears surface projections such as axons, dendrites, cilia, or flagella, excluding the plasma membrane on cell projections.


cluster of actin-based cell projections

description: A cell part consisting of multiple, closely packed actin-based cell projections.


proplastid stroma

description: The space enclosed by the double membrane of a proplastid.


ciliary shaft

description: The mid part of a cilium between the ciliary base and ciliary tip that extends into the extracellular space.


intracellular immature spore

description: A cell or part of the cell that constitutes an early developmental stage of a spore, a small reproductive body that is highly resistant to desiccation and heat and is capable of growing into a new organism, produced especially by certain bacteria, fungi, algae, and nonflowering plants.


male pronucleus

description: The pronucleus originating from the spermatozoa that was involved in fertilization.


rhoptry

description: A large, club-shaped secretory organelle that forms part of the apical complex of an apicomplexan parasite, and consists of a bulbous body and a narrow electron-dense neck that extends through the conoid at the apical tip of the parasite. The rhoptry necks serve as ducts through which the contents of the rhoptries are secreted after attachment to the host has been completed and at the commencement of invasion. Rhoptry proteins function in the biogenesis and host organellar association of the parasitophorous vacuole.


cortical endoplasmic reticulum lumen

description: The volume enclosed by the membranes of the cortical endoplasmic reticulum.


striated muscle thin filament

description: Filaments formed of actin and associated proteins; attached to Z discs at either end of sarcomeres in myofibrils.


gerontoplast stroma

description: Any plastid stroma that is part of a gerontoplast.


axon initial segment

description: Portion of the axon proximal to the neuronal cell body, at the level of the axon hillock. The action potentials that propagate along the axon are generated at the level of this initial segment.


pilus tip

description: The pointed extremity furthest from the cell of a pilus.


postsynaptic specialization

description: A network of proteins within and adjacent to the postsynaptic membrane. Its major components include neurotransmitter receptors and the proteins that spatially and functionally organize them such as anchoring and scaffolding molecules, signaling enzymes and cytoskeletal components.


meiotic spindle pole

description: Either of the ends of a meiotic spindle, a spindle that forms as part of meiosis, where spindle microtubules are organized; usually contains a microtubule organizing center and accessory molecules, spindle microtubules and astral microtubules.


subpellicular network

description: A mechanically stable cytoskeletal structure associated with the cytoplasmic face of the pellicle and surrounding the microtubule-based cytoskeleton.


hydrogenosome lumen

description: The volume enclosed by the hydrogenosome membrane.


recombination nodule

description: An electron dense structure that is associated with meiotic chromosomes.


intermediate layer of spindle pole body

description: Structure between the central and outer plaques of the spindle pole body.


primary cell wall

description: A plant cell wall that is still able to expand, permitting cell growth. Primary cell walls contain more pectin than secondary walls and no lignin is present.


inner mucus layer

description: The inner of two mucus layers secreted by epithelial cells in the colon; the inner mucus layer is firmly attached to the epithelium, is densely packed with a compact stratified appearance and is devoid of bacteria.


S-layer

description: A crystalline protein layer surrounding some bacteria.


kinociliary basal body

description: A ciliary basal body that is part of a kinocilium.


pericellular basket

description: Ramification of basket cell axon surrounding cell bodies, forming the characteristic pericellular baskets from which the cell class derives its name.


half bridge of spindle pole body

description: Structure adjacent to the plaques of the spindle pole body.


glycoprotein network

description: An extracellular matrix part that consists of cross-linked glycoproteins.


acidocalcisome

description: An electron-dense acidic membrane-bounded organelle which contains a matrix of pyrophosphate and polyphosphates with bound calcium and other cations.


endoplasmic reticulum cisternal network

description: A subcompartment of the endoplasmic reticulum consisting of flattened, disc-shaped domains known as cisternae. These are typically found close to the nucleus and are generally more prominent in secretory cells.


podosome ring

description: The ring structure surrounding the podosome core, containing proteins such as vinculin and talin.


outer plaque of spindle pole body

description: One of three laminate structures that form the spindle pole body; the outer plaque is in the cytoplasm.


mitotic spindle midzone

description: The area in the center of the anaphase spindle consisting of microtubules, microtubule bundling factors and kinesin motors where the spindle microtubules from opposite poles overlap in an antiparallel manner.


mossy fiber rosette

description: A synapse of a mossy fiber onto the dendrite of a granule cell; each mossy fiber can have up to 50 rosettes.


plastid membrane

description: Either of the lipid bilayers that surround a plastid and form the plastid envelope.


photoreceptor inner segment

description: The inner segment of a vertebrate photoreceptor containing mitochondria, ribosomes and membranes where opsin molecules are assembled and passed to be part of the outer segment discs.


chloroplast starch grain

description: Plant storage body for amylose and amylopectin, 1-100um in diameter, and located in chloroplasts. Also contains small amounts of enzymes, amino acids, lipids and nucleic acids. The shape of the grain varies widely amongst species, but is often spherical or disk-shaped.


endexine

description: The inner part of the exine, which stains.


name: endoplasmic reticulum tubular network membrane

description: The membrane of the endoplasmic reticulum tubular network.


acroblast

description: A cone-shaped structure in the head of a spermatozoon, which is formed by the coalescence of Golgi fragments following the completion of meiosis. The acroblast is situated adjacent to the acrosomal vesicle.


haustorium

description: A projection from a cell or tissue that penetrates the host's cell wall and invaginates the host cell membrane.


autolysosome lumen

description: The volume that is enclosed within the autolysosome single-membrane.


dendrite terminus

description: A structure at the distal end of a dendrite adapted to carry out a specific function, e.g. dendriole.


terminal bouton

description: Terminal inflated portion of the axon, containing the specialized apparatus necessary to release neurotransmitters. The axon terminus is considered to be the whole region of thickening and the terminal bouton is a specialized region of it.


name: inner plaque of mitotic spindle pole body

description: One of three laminate structures that form the mitotic spindle pole body; the inner plaque is in the nucleus.


extraorganismal space

description: The environmental space outside of an organism; this may be a host organism in the case of parasitic and symbiotic organisms.


basal body patch

description: The region in the apical portion of multiciliated epithelial cells where the ciliary basal bodies cluster.


cofilin-actin rod

description: A cellular structure consisting of parallel, hexagonally arranged actin tubules, comprising filamentous actin and disulfide cross-linked cofilin multimers.


pectic matrix

description: The gel-like pectin matrix consists of the interlinked acidic and neutral pectin networks that are further cross-linked by calcium bridges. Pectins consist largely of long chains of mostly galacturonic acid units (typically 1,4 linkages and sometimes methyl esters). Three major pectic polysaccharides (homogalacturonan, rhamnogalacturonan I and rhamnogalacturonan II) are thought to occur in all primary cell walls.


bounding membrane of organelle

description: The lipid bilayer that forms the outer-most layer of an organelle.


acidocalcisome membrane

description: The lipid bilayer surrounding an acidocalcisome.


photoreceptor inner segment membrane

description: The membrane surrounding the inner segment of a vertebrate photoreceptor. The photoreceptor inner segment contains mitochondria, ribosomes and membranes where opsin molecules are assembled and passed to be part of the outer segment discs.


name: organellar chromatophore intermembrane space

description: The region between the inner and outer lipid bilayers that surround an organellar chromatophore.


type Is terminal bouton

description: Terminal inflated portion of the axon of a glutamatergic neuron, containing the specialized apparatus necessary for the phasic release neurotransmitters that will induce the contraction of muscle. Type Is terminal boutons are smaller than type Ib terminal boutons.


axonal growth cone

description: The migrating motile tip of a growing nerve cell axon.


plasmodesmatal plasma membrane

description: The portion of the plasma membrane surrounding a plasmodesma.


lytic vacuole

description: A vacuole that is maintained at an acidic pH and which contains degradative enzymes, including a wide variety of acid hydrolases.


basal labyrinth

description: A region in the lower half of some cells formed from extensive infoldings of the basal plasma membrane; includes cytoplasm adjacent to the infolded membrane.


presynapse

description: The part of a synapse that is part of the presynaptic cell.


axonemal central pair projection

description: Part of the 9+2 axoneme, that occurs in most motile cilia, consisting of the projections off of the central pair of single microtubules.


mesaxon

description: Portion of the ensheathing process (either myelin or non-myelin) where the enveloping lips of the ensheathing cell come together so that their apposed plasma membranes run parallel to each other, separated by a cleft 12 nm wide.


filopodium tip

description: The end of a filopodium distal to the body of the cell.


name: basal layer of collagen and cuticulin-based cuticle extracellular matrix

description: The layer of cuticle most closely apposed to the hypodermal cells. The morphology of the basal layer varies with life stage. In adult C. elegans animals, the basal layers is comprised of three sublayers: two fibrous layers whose fibers run in clockwise and counter-clockwise directions meeting one another at a 60 degree angle, and an amorphous basal layer that lies underneath the fibrous layers and directly contacts the hypodermis. In C. elegans dauer and L1 larval stage animals, the basal layer is characterized by a striated pattern that appears to derive from interwoven laminae. An example of this component is found in Caenorhabditis elegans.


cell leading edge

description: The area of a motile cell closest to the direction of movement.


macronucleus

description: A membrane-bounded organelle of ciliated protozoan cells that contains polyploid copies of a portion of the cell's complete genome. Transcription of genes occurs in macronuclei. Some ciliate species may contain multiple macronuclei per cell.


cleavage furrow

description: The cleavage furrow is a plasma membrane invagination at the cell division site. The cleavage furrow begins as a shallow groove and eventually deepens to divide the cytoplasm.


ventral disc crossbridge

description: Structure horizontally linking adjacent microribbons of the ventral disc in Giardia species (trophozoite stage). The composition of crossbridges is not fully known yet.


postsynaptic endocytic zone

description: A stably positioned site of clathrin adjacent and physically attached to the postsynaptic specialization, which is the site of endocytosis of post-synaptic proteins.


cyanelle intermembrane space

description: The region between the inner and outer lipid bilayers of the cyanelle envelope; includes the peptidoglycan layer.


longitudinal side of cell surface

description: The side of the cell parallel to the zygotic axis.