metaphase plate

description: The intracellular plane, located halfway between the poles of the spindle, where chromosomes align during metaphase of mitotic or meiotic nuclear division.


tectum

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

description: The layer of sexine which forms a roof over the columella, granules or other infratectal elements.


type IV pilus

description: A short filamentous structure on the surface of a bacterial cell distinguished from other pili by post-translational N-methylation of the pilin monomers.


actomyosin

description: Any complex of actin, myosin, and accessory proteins.


lysosomal glycocalyx

description: The polysaccharide-based coating on the inner side of a lysosomal membrane. It may be involved in protecting the membrane from digestion by lysosomal enzymes.


fusome

description: A large intracellular spectrin-rich structure that has been found in insect germline cells and mammalian hematopoietic cells. The fusome is an elongated, branched structure, formed from the spherical spectrosome organelle.


periplasmic space

description: The region between the inner (cytoplasmic) and outer membrane (Gram-negative Bacteria) or cytoplasmic membrane and cell wall (Fungi and Gram-positive Bacteria).


left tetrad

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


mitochondrial matrix

description: The gel-like material, with considerable fine structure, that lies in the matrix space, or lumen, of a mitochondrion. It contains the enzymes of the tricarboxylic acid cycle and, in some organisms, the enzymes concerned with fatty acid oxidation.


cyanelle membrane

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


bacterial-type flagellum motor

description: A transmembrane complex embedded in the cytoplasmic membrane which is the motor force, or torque, generator of the bacterial-type flagellum. The motor consists of a membrane-anchored rotor complex surrounded by one or more stator complexes in the cytoplasmic membrane. The stator consists of a hetero-hexameric complex of 2 membrane proteins, A and B, with stoichiometry A4B2. Examples are the H+ driven MotA-MotB stator complex of Escherichia coli and Salmonella enterica, and the Na+ driven PomA-PomB stator complex of Vibrio and Shewanella species. The rotor complex consists of a membrane-anchored ring and the motor switch complex, which controls the direction of flagellar rotation.


omegasome

description: Omega-shaped (as in the Greek capital letter) intracellular membrane-bounded organelle enriched in phosphatidylinositol 3-phosphate and dynamically connected to the endoplasmic reticulum. Omegasomes are the first step of the formation of autophagosomes via the phagophore assembly sites.


extrachromosomal DNA

description: DNA structures that are not part of a chromosome.


name: axonemal microtubule doublet inner sheath

description: A structural network of microtubule inner proteins (MIPs) located inside the lumens of the A and B tubules of the axonemal microtuble doublet that helps stabilize the doublet microtubule.


host cell postsynaptic membrane

description: A postsynaptic membrane that is part of a host cell. A postsynaptic membrane is 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 transmit the signal across the synaptic cleft to the postsynaptic membrane.


spindle envelope

description: An organelle envelope that surrounds the chromosomes and the central part of the spindle apparatus during mitosis and meiosis; observed in many invertebrates. The spindle envelope consists of membrane layers, called parafusorial membranes, derived from endoplasmic reticulum membrane; in male meiosis it forms during prometaphase and persists until early in the ensuing interphase.


growth cone

description: The migrating motile tip of a growing neuron projection, where actin accumulates, and the actin cytoskeleton is the most dynamic.


hyaluranon cable

description: A cable structure, surrounding some cell types (e.g. proximal or bronchial tubular epithelial cells), and composed of hyaluranon (HA), a ubiquitous connective tissue glycosaminoglycan.


non-growing cell tip

description: A cell tip at which no growth takes place. For example, in fission yeast the cell end newly formed by cell division does not grow immediately upon its formation, and lacks actin cytoskeletal structures.


periciliary membrane compartment

description: A plasma membrane region adjacent to the base of eukaryotic cilia and flagella that is enriched in endocytosis-associated proteins and vesicles and that appears to regulate ciliary membrane homeostasis.


starch grain

description: Plant storage body for amylose and amylopectin, 1-100um in diameter. 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.


mitochondrial intermembrane space

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


name: photoreceptor proximal connecting cilium

description: The proximal region of the photoreceptor connecting cilium is similar to the transition zone of unspecialized primary cilia and houses several major transition zone complexes, including NPHP, MKS, and RPGR.


name: perforant pathway to dendrate granule cell synapse

description: A neuron to neuron synapse of a pyramidal neuron in the entorhinal cortex onto a granule cell in the dentate gyrus of the hippocampus.


axolemma

description: The portion of the plasma membrane surrounding an axon; it is a specialized trilaminar random mosaic of protein molecules floating within a fluid matrix of highly mobile phospholipid molecules, 7-8 nm in thickness.


Woronin body

description: Peroxisome-derived dense-core vesicle that seals septal pores upon hyphal lysis to prevent excessive cytoplasmic loss. It is specific to several genera of filamentous ascomycetes.


meiotic spindle pole body

description: The microtubule organizing center that forms as part of the meiotic cell cycle; functionally homologous to the animal cell centrosome.


muscle cell projection membrane

description: The portion of the plasma membrane surrounding a muscle cell projection.


Isp3 layer of spore wall

description: The outermost layers of the spore wall, as described in Schizosaccharomyces pombe.


granular component

description: A structure found in the nucleolus, which contains nearly completed preribosomal particles destined for the cytoplasm.


spine mat

description: A configuration of neuron spines found on ciliary ganglion neurons in the embryonic and adult brain consisting of patches of closely spaced spines lying flat against the soma.


DIM/DIP cell wall layer

description: A section of the Actinobacterium-type cell wall composed of (phenyl)phthiocerol, phthiodiolone, phthiotriol dimycocerosate, diphthioceranate and other compounds.


microvesicle

description: An extracellular vesicle released from the plasma membrane and ranging in size from about 100 nm to 1000 nm.


stereocilium bundle

description: A bundle of cross-linked stereocilia, arranged around a kinocilium on the apical surface of a sensory hair cell (e.g. a neuromast, auditory or vestibular hair cell). Stereocilium bundles act as mechanosensory organelles by responding to fluid motion or fluid pressure changes.


ciliary pro-basal body

description: The cilary pro-basal body is an immature, partially assembled form of a ciliary basal body found next to the basal body of a cilium. Pro-basal bodies are not capable of nucleating a cilium. As the cell progresses through the cell cycle, continuing assembly will convert the pro-basal body into a mature basal body that is capable of nucleating a cilium.


ciliary inversin compartment

description: Proximal part of the ciliary shaft to which the inversin protein (also called Inv) specifically localizes. The inversin compartment appears to have a different protein composition than the rest of the cilium, although there is no structure that separates it form the distal part of the cilium.


plastid stroma

description: The proteinaceous ground substance of plastids.


rhoptry lumen

description: The volume enclosed by the rhoptry membrane.


replication fork

description: The Y-shaped region of a 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.


left posteriolateral basal body

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


dendriole

description: Small dendrites that makes up a brush structure found as the terminal specialization of a dendrite of a unipolar brush cell (UBC).


plasma membrane of growing cell tip

description: Any plasma membrane part that is part of a growing cell tip.


spongiome

description: A cellular anatomical entity which is a network of tubules and vessicles and is part of the contractile vacuole complex. It is involved in the discharge of water externally. One of its functions is osmoregulatory.


Golgi stack lumen

description: The volume enclosed by any of the membranes of the thin, flattened cisternae that form the central portion of the Golgi complex.


antipodal cell nucleus

description: The nucleus of an antipodal cell, one of three cells of the embryo sac in angiosperms, found at the chalazal end of the embryo away from the point of entry of the pollen tube, and its descendents.


sperm midpiece

description: The highly organized segment of the sperm flagellum which begins at the connecting piece and is characterized by the presence of 9 outer dense fibers (ODFs) that lie outside each of the 9 outer axonemal microtubule doublets and by a sheath of mitochondria that encloses the ODFs and the axoneme; the midpiece terminates about one-fourth of the way down the sperm flagellum at the annulus, which marks the beginning of the principal piece.


costamere

description: Regular periodic sub membranous arrays of vinculin in skeletal and cardiac muscle cells, these arrays link Z-discs to the sarcolemma and are associated with links to extracellular matrix.


glycogen granule

description: Cytoplasmic bead-like structures of animal cells, visible by electron microscope. Each granule is a functional unit with the biosynthesis and catabolism of glycogen being catalyzed by enzymes bound to the granule surface.


pollen wall

description: The wall surrounding a mature pollen grain; a multilayered structure consisting of a pectocellulosic intine surrounded by a sporopollenin-based exine, which itself contains two layers, the inner nexine and the outer sexine.


host cell part

description: Any constituent part of a host cell. The host is defined as the larger of the organisms involved in a symbiotic interaction.


cellular bud tip

description: The end of a cellular bud distal to the site of attachment to the mother cell.


slime layer

description: A slime layer is an easily removed, diffuse, unorganized layer of extracellular material that surrounds a cell. Specifically this consists mostly of exopolysaccharides, glycoproteins, and glycolipids.


DNA replication termination region

description: A chromosomal region that contains fork pausing elements influencing the progression and merging of DNA replication forks.


sperm head-tail coupling apparatus

description: A centrosome-based structure consisting of two cylindrical microtubule-based centrioles and associated components which anchors the flagellum to the sperm head.


host cell envelope

description: An envelope that surrounds a bacterial host cell and includes the host cytoplasmic membrane and everything external, encompassing the host periplasmic space, host cell wall, and host outer membrane if present.


satellite fibril

description: An axoneme part that is found in the flagella of mammalian sperm and is located in the middle piece between the outer dense fibers (on the concave side of outer dense fibers as seen in cross-section).


chitosan layer of spore wall

description: The second outermost layer of the spore wall, as described in Saccharomyces.


cell junction

description: A cellular component that forms a specialized region of connection between two or more cells, or between a cell and the extracellular matrix, or between two membrane-bound components of a cell, such as flagella.


presynaptic grid

description: A hexagonal array of electron dense particles attached to the cytoplasmic face of the presynaptic membrane.


sperm head plasma membrane

description: The plasma membrane that is part of the head section of a sperm cell.


ciliary pocket collar

description: A constriction site at the junction of the plasma, flagellar and flagellar pocket membranes where the flagellum emerges from the cell body. Observed in some unicellular eukaryotic species such as Chlamydomonas, Giardia and Trypanosoma.


rod bipolar cell terminal bouton

description: A specialized region of the axon terminus portion of a rod bipolar axon. A rod bipolar cell is a neuron found in the retina and having connections with rod photoreceptor cells and neurons in the inner plexiform layer.


vascular endothelial glycocalyx

description: The carbohydrate-rich layer lining the vascular endothelium connected to the endothelium through a variety of molecules, mainly proteoglycans and glycoproteins. These form a network in which soluble molecules, either plasma- or endothelium-derived, are incorporated.


immunological synapse

description: An area of close contact between a lymphocyte (T-, B-, or natural killer cell) and a target cell formed through the clustering of particular signaling and adhesion molecules and their associated membrane rafts on both the lymphocyte and the target cell and facilitating activation of the lymphocyte, transfer of membrane from the target cell to the lymphocyte, and in some situations killing of the target cell through release of secretory granules and/or death-pathway ligand-receptor interaction.


basal part of cell

description: The region of a cell situated near the base. For example, in a polarized epithelial cell, the basal surface rests on the basal lamina that separates the epithelium from other tissue.


capsule

description: A protective structure surrounding some fungi and bacteria, attached externally to the cell wall and composed primarily of polysaccharides. Capsules are highly organized structures that adhere strongly to cells and cannot be easily removed. Capsules play important roles in pathogenicity, preventing phagocytosis by other cells, adherence, and resistance to desiccation.


name: bacterial-type flagellum hook-filament junction

description: The region of the bacterial-type flagellum where the hook and filament meet.


female pronucleus

description: The pronucleus originating from the ovum that is being fertilized.


M band

description: The midline of aligned thick filaments in a sarcomere; location of specific proteins that link thick filaments. Depending on muscle type the M band consists of different numbers of M lines.


C bouton

description: Synaptic bouton found in spinal cord on the soma and proximal dendrites of motor neurons.


organelle inner membrane

description: The inner, i.e. lumen-facing, lipid bilayer of an organelle envelope; usually highly selective to most ions and metabolites.


ciliary basal body

description: A membrane-tethered, short cylindrical array of microtubules and associated proteins found at the base of a eukaryotic cilium (also called flagellum) that is similar in structure to a centriole and derives from it. The cilium basal body is the site of assembly and remodeling of the cilium and serves as a nucleation site for axoneme growth. As well as anchoring the cilium, it is thought to provide a selective gateway regulating the entry of ciliary proteins and vesicles by intraflagellar transport.


plastid thylakoid lumen

description: The volume enclosed by a plastid thylakoid membrane.


sporoplasm

description: The complex infective apparatus corresponding to the central mass of cytoplasm within a spore that is injected into a host cell by various parasitic microorganisms.


sperm principal piece

description: The segment of the sperm flagellum where the mitochondrial sheath ends, and the outer dense fibers (ODFs) associated with outer axonemal doublets 3 and 8 are replaced by the 2 longitudinal columns of the fibrous sheath (FS) which run the length of the principal piece and are stabilized by circumferential ribs. The principal piece makes up ~2/3 of the length of the sperm flagellum and is defined by the presence of the FS and of only 7 (rather than 9) ODFs which taper and then terminate near the distal end of the principal piece.


cone matrix sheath

description: A biochemically and structurally distinct domain of the retinal interphotoreceptor matrix that is specifically associated with cone photoreceptor cell inner and outer segments.


nexine

description: The inner, non-sculptured part of the exine which lies below the sexine.


ring centriole

description: A ring-like structure observed at the base of the ciliary cap of insect spermatids. This structure may anchor the axoneme to the ciliary cap membrane and/or act as a diffusion barrier, proposed to be analogous to the annulus of mammalian sperm flagellum.


meiotic 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 meiotic 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 meiotic contractile ring is located inside the plasma membrane at the location of the cleavage furrow. In fungal cells, the meiotic contractile ring forms beneath the plasma membrane of the prospore envelope in preparation for completing cytokinesis.


stromule

description: Thin filamentous structure extending from the surface of all plastid types examined so far, including chloroplast, proplastid, etioplast, leucoplast, amyloplast, and chromoplast. In general, stromules are more abundant in tissues containing non-green plastids, and in cells containing smaller plastids. The primary function of stromules is still unresolved, although the presence of stromules markedly increases the plastid surface area, potentially increasing transport to and from the cytosol. Other functions of stromules, such as transfer of macromolecules between plastids and starch granule formation in cereal endosperm, may be restricted to particular tissues and cell types.


ventral disc lateral crest

description: Fibrillar repetitive structure surrounding the ventral disc edge in Giardia species (trophozoite stage). The composition of the lateral crest is not fully known yet.


prospore membrane leading edge

description: The region of the prospore membrane that extends to surround the spore nucleus; coated with specific proteins that are thought to play a role in prospore membrane organization.


main axon

description: The main axonal trunk, as opposed to the collaterals; i.e., excluding collaterals, terminal, spines, or dendrites.


smooth muscle dense body

description: Electron-dense region associated with a smooth muscle contractile fiber.


paranode region of axon

description: An axon part that is located adjacent to the nodes of Ranvier and surrounded by lateral loop portions of myelin sheath.


dendrite membrane

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


unicellular trichome branch

description: A cell projection part that is a branch of a unicellular trichome.


lateral loop

description: Non-compact myelin located adjacent to the nodes of Ranvier in a myelin segment. These non-compact regions include cytoplasm from the cell responsible for synthesizing the myelin. Lateral loops are found in the paranodal region adjacent to the nodes of Ranvier, while Schmidt-Lantermann clefts are analogous structures found within the compact myelin internode.


peptidoglycan-based cell wall

description: A protective structure outside the cytoplasmic membrane composed of peptidoglycan (also known as murein), a molecule made up of a glycan (sugar) backbone of repetitively alternating N-acetylglucosamine and N-acetylmuramic acid with short, attached, cross-linked peptide chains containing unusual amino acids. An example of this component is found in Escherichia coli.


description: An organelle arrangement comprised of the following elements: a mitochondrion positioned near the presynaptic membrane; an electron-dense mitochondrial plaque adjacent to the outer mitochondrial membrane that faces the presynaptic membrane; filament-like elements appearing to link the mitochondrial plaque to a cell-cell junction region (sometimes termed punctum adherens); tubular or vesicular-appearing membrane (also called vesicular chain) interposed among the filaments. Mitochondrion-associated adherens complexes were initially described in the dorsal horn of the spinal cord. They are found in calyces and other large terminals of the auditory brainstem, and in a variety of mammalian species including humans.


mitochondrial intracristal space

description: The space bounded by the mitochondrial cristae membranes, continuous with the intermembrane space.


pinceau fiber

description: Dense plexus formed by the descending collaterals of cerebellar basket cells that wrap around a Purkinje cell axonal initial segment.


neuron projection membrane

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


nuclear lumen

description: The volume enclosed by the nuclear inner membrane.


attachment organelle

description: A membrane-bounded extension of the cell, originally characterized in Mycoplasma species, that contains an electron-dense core that is part of the cytoskeleton and is oriented lengthwise and ends distally in a bulbous knob (terminal button). Required for adherence to host cells and involved in gliding motility and cell division.


actin cap

description: Polarized accumulation of cytoskeletal proteins (including F-actin) and regulatory proteins in a cell. An example of this is the actin cap found in Saccharomyces cerevisiae.


nuclear periphery

description: The portion of the nuclear lumen proximal to the inner nuclear membrane.


cell septum edging

description: The cell wall material that surrounds the septum in fungal cells.


external encapsulating structure

description: A structure that lies outside the plasma membrane and surrounds the entire cell or cells. This does not include the periplasmic space.


varicosity

description: Non-terminal inflated portion of the axon, containing the specialized apparatus necessary to release neurotransmitters.


annulate lamellae

description: Stacks of endoplasmic reticulum (ER) membranes containing a high density of nuclear pores, thought to form from excess nuclear membrane components, that have been described in a number of different cells. Annulate lamellar membranes are continuous with and embedded within the ER.


intracellular anatomical structure

description: A component of a cell contained within (but not including) the plasma membrane. In eukaryotes it includes the nucleus and cytoplasm.


ventral disc dorsal microribbon

description: Trilaminar structure extending perpendicularly into the cytoplasm along the length of ventral disc microtubules in Giardia species (trophozoite stage). Constituents of dorsal microribbons (also called dorsal ribbons or microribbons) include alpha-coiled-helix proteins approximately 29 to 38 kDa in size. These proteins line the edges of the microribbons but are not found in microtubules. Tubulins are not found in microribbons.


porosome

description: A permanent cup-shaped structure at the cell plasma membrane in secretory cells. Following a secretory stimulus, secretory vesicles transiently dock and fuse at the base of porosomes and release intravesicular contents dictated by the turgor pressure generated from the swelling of secretory vesicles.


organelle lumen

description: The internal volume enclosed by the membranes of a particular organelle; includes the volume enclosed by a single organelle membrane, e.g. endoplasmic reticulum lumen, or the volume enclosed by the innermost of the two lipid bilayers of an organelle envelope, e.g. nuclear lumen.


leading edge membrane

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


name: nuclear outer membrane-endoplasmic reticulum membrane network

description: The continuous network of membranes encompassing the nuclear outer membrane and the endoplasmic reticulum membrane.


longitudinal sarcoplasmic reticulum

description: The portion of the free sarcoplasmic reticulum consisting of longitudinal tubules that connect terminal cisternae.


left middle basal body pair

description: Set of two basal bodies found in Giardia species (trophozoite stage). It comprises the caudal and posteriolateral basal bodies located to the right of the left nucleus of the trophozoite when viewed dorsally.


pericentriolar material

description: A network of small fibers that surrounds the centrioles in cells; contains the microtubule nucleating activity of the centrosome.


presynaptic endocytic zone membrane

description: The region of the presynaptic membrane that is part of the presynaptic endocytic zone - where synaptic vesicles are endocytosed and recycled following release.


cortical endoplasmic reticulum

description: A cortical network of highly dynamic tubules that are juxtaposed to the plasma membrane and undergo ring closure and tubule-branching movements.


median body

description: A non-membrane bound, semi-organized microtubule array of unknown function found in Giardia species (trophozoite stage). It is located on the dorsal side of the trophozoite, slightly posterior to the ventral disc.


mononeme

description: A secretory organelle that forms part of the apical complex; a small, threadlike structure located is close proximity to the subpellicular microtubules. Its contents include a rhomboid protease (PfROM1 in Plasmodium falciparum) that moves from the lateral asymmetric localization to the merozoite apical pole and the posterior pole upon release of merozoites from schizonts.


glyoxysome

description: A specialized form of peroxisome that contains the enzymes of the glyoxylate pathway. The glyoxysome is found in some plant cells, notably the cells of germinating seeds.


ciliary rootlet

description: A cytoskeleton-like structure, originating from the basal body at the proximal end of a cilium, and extending proximally toward the cell nucleus. Rootlets are typically 80-100 nm in diameter and contain cross striae distributed at regular intervals of approximately 55-70 nm.


stereocilia tip-link density

description: An electron-dense plaque at either end of a stereocilia tip link that provides the anchor in the stereocilia membrane.


preprophase band

description: A dense band of microtubules, 1-3 pm wide, that appears just beneath the cell membrane before the start of cell division in the cells of higher plants. It precedes the onset of prophase and then disappears as mitosis begins, yet it somehow determines the plane of orientation of the new cell plate forming in late telophase and marks the zone of the parental cell wall where fusion with the growing cell plate ultimately occurs.


inner plaque of spindle pole body

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


mating projection septin band

description: A septin band, i.e. a diffuse ring composed of a series of septin bars running parallel to the long axis of the cell, located at the neck of a shmoo (mating projection).


stereocilia ankle link

description: A stereocilia coupling link that is composed of a fine filament present in developing stereocilia that couples the bases of individual stereocilia to one another. They are not present in mature stereocilia.


stereocilium base

description: The tapered base of the stereocilium adjacent to where it joins the hair cell body. This region contains a rootlet comprised of bundled actin filaments which spans the joint and stabilizes the stereocilium.


phagocytic cup base

description: The older part of the phagocytic cup where the actin cytoskeleton disassembles, allowing early incoming and outgoing vesicular trafficking.


apical complex

description: A group of cytoskeletal structures and associated membrane-bounded organelles found at the anterior end of adult obligate intracellular protozoan parasites in the phylum Apicomplexa. The apical complex is involved in attachment to and penetration of the host cell, and in parasite proliferation.


microtubule organizing center

description: An intracellular structure that can catalyze gamma-tubulin-dependent microtubule nucleation and that can anchor microtubules by interacting with their minus ends, plus ends or sides.


ocelloid

description: Eye-like subcellular structure found in dinoflagellates (a large group of single-celled eukaryotes). Consists of subcellular analogues to a cornea, lens, iris, and retina. Ocelloids are built from pre-existing organelles, including a cornea-like layer made of mitochondria and a retinal body made of anastomosing plastids.


endosome lumen

description: The volume enclosed by the membrane of an endosome.


exoneme

description: A dense granule-like organelle of the apical complex of merozoites, released into the parasitophorous vacuole, mediating protease-dependent rupture and parasite exit from the infected erythrocyte.


juxtaparanode region of axon

description: A region of an axon near a node of Ranvier that is between the paranode and internode regions.


hyphal membrane

description: A host-derived membrane surrounding the symbiont hypha during infection.


bacterial-type flagellum filament cap

description: The proteinaceous structure at the distal tip of the bacterial-type flagellar filament.


description: Organized structure of distinctive morphology and function, bounded by a lipid bilayer membrane and occurring outside the cell.


magnetosome lumen

description: The volume enclosed by the membrane of a magnetosome.


glutamatergic synapse

description: A synapse that uses glutamate as a neurotransmitter.


axonemal B tubule inner sheath

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


primary cell septum

description: A cell septum that forms following nuclear division.


virus-like capsid

description: A protein coat that surrounds nucleic acid to form a structure similar to a virus capsid. Virus-like capsids are non-infectious and are encoded by endogenous (non-viral) genes. Fly and tetrapod Arc (ancestrally-related to retrotransposon Gag) are examples of proteins that can self-assemble into capsid-like structures which encapsulate Arc mRNA and mediate the intercellular transmission of RNA.


postsynaptic density

description: An electron dense network of proteins within and adjacent to the postsynaptic membrane of an asymmetric, neuron-neuron synapse. 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.


subplasmalemmal coating

description: Electron dense material observed coating the cytoplasmic face of the plasma membrane in certain regions of a neuron, e.g., the axon initial segment; the nodal membrane at the Node of Ranvier.


presynaptic active zone

description: A specialized region of the plasma membrane and cell cortex of a presynaptic neuron; encompasses a region of the plasma membrane where synaptic vesicles dock and fuse, and a specialized cortical cytoskeletal matrix.


cellularization cleavage furrow

description: A plasma membrane invagination at the site of separation of a multi-nucleate cell or syncytium into individual cells.


basolateral part of cell

description: The region of a cell situated by the cell sides which interface adjacent cells and near the base. Often used in reference to animal polarized epithelial cells.


stereocilium shaft

description: The shaft comprises the majority of the length of the stereocilium. This region is notable for the extreme stability of actin filaments, which are highly crosslinked into a parallel bundle.


medial cortical node

description: A component of the cell division site that contains the mid1, cdr2, wee1, klp8, and blt1 proteins, and is involved in contractile ring localization. Medial cortical node complexes appear as cortical dots in the middle of the cell during interphase, and function to recruit other ring components in early mitosis.


compact myelin

description: The portion of the myelin sheath in which layers of cell membrane are tightly juxtaposed, completely excluding cytoplasm. The juxtaposed cytoplasmic surfaces form the major dense line, while the juxtaposed extracellular surfaces form the interperiod line visible in electron micrographs.


reservosome matrix

description: A matrix composed of planar membranes, vesicles and lipid inclusions within the reservosome.


cortical dynamic polarity patch

description: A region of the cell cortex that contains a higher concentration of growth polarity factors than the surrounding cortex and that changes position over time. An example is found in fission yeast cells during early mating, in which the GTPase Cdc42 dynamically to discrete zones within the cortex prior to shmoo formation.


centrosomal core

description: The core region of the centrosome, a layered structure containing proteins, surrounded by the centrosomal corona. The core duplicates once per cell cycle at the G2/M transition when two outer layers form the mitotic spindle poles.


stereocilia coupling link

description: A structure involved in coupling stereocilia to one another in sensory hair cells There are four morphologically distinct types: tip links, horizontal top connectors, shaft connectors and ankle links. Tip links and horizontal top connectors are the only inter-stereocilia links associated with mature cochlea, whereas ankle links appear during development of the auditory hair bundle.


postsynaptic endocytic zone membrane

description: The region of the postsynaptic membrane that is part of the postsynaptic endocytic zone. This region of membrane is associated with stable clathrin puncta.


germinal vesicle

description: The enlarged, fluid filled nucleus of a primary oocyte, the development of which is suspended in prophase I of the first meiotic division between embryohood and sexual maturity.


organelle membrane

description: A membrane that is one of the two lipid bilayers of an organelle envelope or the outermost membrane of single membrane bound organelle.


outer dense plaque of desmosome

description: The desmosomal part containing plakoglobins, plakophilins, the N-termini of desmoplakins, as well as the cytoplasmic tails of the desmosomal cadherins, which together attach the plaque to the plasma membrane.


ciliary base

description: Area of the cilium (also called flagellum) where the basal body and the axoneme are anchored to the plasma membrane. The ciliary base encompasses the distal part of the basal body, transition fibers and transition zone and is structurally and functionally very distinct from the rest of the cilium. In this area proteins are sorted and filtered before entering the cilium, and many ciliary proteins localize specifically to this area.


name: organellar chromatophore thylakoid lumen

description: The volume enclosed by an organellar chromatophore thylakoid membrane.


etioplast membrane

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


hyphal cell wall

description: The cell wall surrounding a fungal hypha.


synapse

description: The junction between an axon of one neuron and a dendrite of another neuron, a muscle fiber or a glial cell. As the axon approaches the synapse it enlarges into a specialized structure, the presynaptic terminal bouton, which contains mitochondria and synaptic vesicles. At the tip of the terminal bouton is the presynaptic membrane; facing it, and separated from it by a minute cleft (the synaptic cleft) is a specialized area of membrane on the receiving cell, known as the postsynaptic membrane. In response to the arrival of nerve impulses, the presynaptic terminal bouton secretes molecules of neurotransmitters into the synaptic cleft. These diffuse across the cleft and transmit the signal to the postsynaptic membrane.


Schaffer collateral - CA1 synapse

description: A synapse between the Schaffer collateral axon of a CA3 pyramidal cell and a CA1 pyramidal cell.


host intracellular region

description: That space within the plasma membrane of a host cell.


retrotransposon nucleocapsid

description: A complex of the retrotransposon RNA genome, reverse transcriptase, integrase, and associated molecules required for reproduction and integration of the retrotransposon into the host genome; the main structural molecule of the nucleocapsid is often a gag protein homolog.


stereocilium coat

description: A glycocalyx on the the endolymphatic surface of a cochlear hair cell that coats the external surface of each stereocilium and maintains a small distance between adjacent stereocilia in the bundle.


symmetric synapse

description: A synapse that lacks an electron dense postsynaptic specialization. In vertebtrates, these occur primarily on dendrite shafts and neuronal cell bodies and involve persynapses containing clusters of predominantly flattened or elongated vesicles and are typically inhibitory.


mitochondrial membrane scission site

description: The site on the mitochondrial membrane where the separation of a single continuous mitochondrial membrane into two membranes occurs as a final step in mitochondrial fission.


extracellular vesicle

description: Any vesicle that is part of the extracellular region.


acidocalcisome lumen

description: The volume enclosed by the membranes of an acidocalcisome.


basolateral cytoplasm

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


deep fiber

description: Inward projections of the cytoskeletal structures of the oral apparatus, which form a fiber that extends past the cytostome into the cytoplasm.


neuron to neuron synapse

description: A synapse in which pre and post-synaptic cells are neurons.


name: hinge region between urothelial plaques of apical plasma membrane

description: A narrow rim of non-thickened membrane in between urothelial plaques in apical plasma membrane.


plant-type vacuole lumen

description: The volume enclosed within the vacuolar membrane of a vacuole that retains the same shape regardless of cell cycle phase. An example of this is found in Arabidopsis thaliana.


name: bacterial-type flagellum secretion apparatus

description: A part of the bacterial-type flagellum that is located at the cytoplasmic side of the MS ring and composed of six membrane proteins (FlhA, FlhB, FliP, FliQ, FliR, and FliO, or orthologs thereof) and three soluble proteins (FliI, FliH, and FliJ, or orthologs thereof) in the cytoplasm. It is responsible for secretion of flagellar type III protein substrates, including the proteins of the flagellar rod, hook, and filament.


axon hillock

description: Portion of the neuronal cell soma from which the axon originates.


annuli extracellular matrix

description: The extracellular matrix that is a regularly spaced circumferential ridge present in the cortical region of the cuticle. Annuli are delineated by annular furrows and are present throughout the cuticle with the exception of lateral regions where longitudinal alae are present.


synaptonemal complex

description: A proteinaceous scaffold found between homologous chromosomes during meiosis. It consists of 2 lateral elements and a central element, all running parallel to each other. Transverse filaments connect the lateral elements to the central element.


basal pole of outer hair cell

description: The end of the outer hair cell which receives and transmits neural signals.


arbuscule

description: Highly branched symbiont haustoria within host root cortex cells, responsible for nutrient exchange.


host peribacteroid fluid

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


plasma membrane of cell tip

description: The portion of the plasma membrane surrounding the cell tip.


mitotic spindle pole

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


sarcoplasmic reticulum membrane

description: The lipid bilayer surrounding the sarcoplasmic reticulum.


serotonergic synapse

description: A synapse that uses serotonin as a neurotransmitter.


neuronal cell body membrane

description: The plasma membrane of a neuron cell body - excludes the plasma membrane of cell projections such as axons and dendrites.


apoptotic body

description: A vesicle containing parts of a dying cell. Apoptotic bodies can be formed during the execution phase of the apoptotic process, when the cell's cytoskeleton breaks up and causes the membrane to bulge outward. These bulges may separate from the cell, taking a portion of cytoplasm with them, to become apoptotic bodies. These are then engulfed by phagocytic cells, and their components recycled. Apoptotic bodies may range in size from 0.8 to 5um.


spindle midzone

description: The area in the center of the spindle where the spindle microtubules from opposite poles overlap.


name: mitotic nuclear bridge midzone membrane domain

description: A nuclear membrane part at the midzone of the mitotic nuclear bridge. The midzone forms a bulge that is enriched in nuclear pores that lack baskets.


basolateral plasma membrane

description: The region of the plasma membrane that includes the basal end and sides of the cell. Often used in reference to animal polarized epithelial membranes, where the basal membrane is the part attached to the extracellular matrix, or in plant cells, where the basal membrane is defined with respect to the zygotic axis.


microbody membrane

description: The lipid bilayer surrounding a microbody.


dendritic growth cone

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


blood microparticle

description: A phospholipid microvesicle that is derived from any of several cell types, such as platelets, blood cells, endothelial cells, or others, and contains membrane receptors as well as other proteins characteristic of the parental cell. Microparticles are heterogeneous in size, and are characterized as microvesicles free of nucleic acids.


right anterior basal body

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


Schmidt-Lanterman incisure

description: Regions within compact myelin in which the cytoplasmic faces of the enveloping myelin sheath are not tightly juxtaposed, and include cytoplasm from the cell responsible for making the myelin. Schmidt-Lanterman incisures occur in the compact myelin internode, while lateral loops are analogous structures found in the paranodal region adjacent to the nodes of Ranvier.


basal plasma membrane

description: The region of the plasma membrane located at the basal end of the cell. Often used in reference to animal polarized epithelial membranes, where the basal membrane is the part attached to the extracellular matrix, or in plant cells, where the basal membrane is defined with respect to the zygotic axis.


presynaptic endocytic zone

description: A specialized region of the plasma membrane and underlying cytoplasm which surround the the active zone, into which synaptic vesicle membranes are recycled following exocytosis. It is especially enriched in endocytic proteins following intense activity.


dendritic spine head

description: Distal part of the dendritic spine, that carries the post-synaptic density.


name: extrinsic component of cell outer membrane

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


cell tip

description: The region at the end of the longest axis of a cylindrical or elongated cell.


central cylinder

description: A scaffolding structure present within the inner region of the ciliary transition zone. The central cylinder lies between the outer doublet and inner singlet microtubules.


polar nucleus

description: Either of two nuclei located centrally in a flowering plant embryo sac that eventually fuse to form the endosperm nucleus.


ciliary transition zone

description: A region of the cilium between the basal body and proximal segment that is characterized by Y-shaped assemblages that connect axonemal microtubules to the ciliary membrane. The ciliary transition zone appears to function as a gate that controls ciliary membrane composition and separates the cytosol from the ciliary plasm.


name: mitotic actomyosin contractile ring, proximal layer

description: The region of the mitotic actomyosin ring adjacent to the plasma membrane where membrane bound scaffolds are located.


mating projection actin fusion focus

description: A focus at the mating projection tip where the cell wall is degraded during conjugation with cellular fusion. Actin filaments form an aster-like structure from this location.


growth cone membrane

description: The portion of the plasma membrane surrounding a growth cone.


external side of cell wall

description: The side of the cell wall that is opposite to the side that faces the cell and its contents.


early recombination nodule

description: An electron dense structure that is associated with meiotic chromosomes in leptotene or zygotene during meiosis I.


name: bacterial-type flagellum basal body, distal rod, L ring

description: One of the rings of the bacterial-type flagellar basal body; anchors the basal body to the outer membrane.


right posteriolateral basal body

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


gut granule lumen

description: The lumen of a gut granule, a lysosome-related organelle contained within the intestinal cells of the nematode C. elegans.


protein storage vacuole lumen

description: The volume enclosed by the protein storage vacuole membrane.


cone photoreceptor outer segment

description: The outer segment of a vertebrate cone photoreceptor that contains membrane discs that are contiguous with the ciliary membrane and containing opsin photoreceptor proteins.


autophagosome lumen

description: The volume enclosed within the autophagosome double-membrane.


plasmodesmatal desmotubule

description: A tightly wound cylinder of membrane that is located within the plasmodesmal pore and runs the length of the plasmodesma. The desmotubule likely provides a rigid stability to plasmodesmata and confers a fixed diameter and pore size to the plasmodesmal canal, and is linked to the endoplasmic reticulum in each of the adjacent cell.


smooth endoplasmic reticulum lumen

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


sexine

description: The outer, sculptured layer of the exine, which lies above the nexine.


septal periplasm

description: The region between the plasma membrane and the cell wall, as found in organisms such as filamentous fungi.


dopaminergic synapse

description: A synapse that uses dopamine as a neurotransmitter.


platelet dense tubular network membrane

description: The lipid bilayer surrounding the platelet dense tubular network.


noradrenergic synapse

description: A synapse that uses noradrenaline as a neurotransmitter.


description: The part of the sarcoplasmic reticulum membrane that contains calcium release channels, is devoted to calcium release and is juxtaposed to transverse tubule membrane. The junctional sarcoplasmic reticulum membrane consists of the junctional region of the terminal cisterna membrane.


symplast

description: The interconnected cell membranes and intracellular regions of a plant. The interconnections occur via the plasmodesmata.


name: postsynaptic specialization of symmetric synapse

description: A network of proteins within and adjacent to the postsynaptic membrane of a symmetric synapse, consisting of anchoring and scaffolding molecules, signaling enzymes and cytoskeletal components that spatially and functionally organize the neurotransmitter receptors at the synapse. This structure is not as thick or electron dense as the postsynaptic densities found in asymmetric synapses.


endoplasmic reticulum subcompartment

description: A distinct region of the endoplasmic reticulum.


xanthophore

description: A chromatophore containing yellow pigment.


name: perinuclear endoplasmic reticulum membrane

description: The membrane of the perinuclear endoplasmic reticulum, which is the portion of endoplasmic reticulum, the intracellular network of tubules and cisternae, that occurs near the nucleus.


secondary cell septum

description: Cell wall structures composed of linear polysaccharides which are deposited at both sides of the primary septum at 90 degrees to the primary septum.


mitotic nuclear bridge stalk

description: Either of the regions of a mitotic nuclear bridge proximal to the main portion of each daughter nucleus. The nuclear envelope in the stalk regions is depleted of nuclear pore complexes.


cytoplasmic side of nuclear pore

description: The side of the nuclear pore complex (NPC) that faces the cytoplasm.


right nucleus

description: One of the two nuclei found in Giardia species (trophozoite stage). It is located on the right side of the cell when viewed from the dorsal side.


dityrosine layer of spore wall

description: The outermost layer of the spore wall, as described in Saccharomyces.


nuclear lamina

description: The fibrous, electron-dense layer lying on the nucleoplasmic side of the inner membrane of a cell nucleus, composed of lamin filaments. The polypeptides of the lamina are thought to be concerned in the dissolution of the nuclear envelope and its re-formation during mitosis. The lamina is composed of lamin A and lamin C filaments cross-linked into an orthogonal lattice, which is attached via lamin B to the inner nuclear membrane through interactions with a lamin B receptor, an IFAP, in the membrane.


peripheral region of growth cone

description: The non-central region or periphery of the migrating motile tip of a growing nerve cell axon or dendrite.


yolk

description: The cytoplasmic part that serves as a nutrient reserve or energy source for the developing embryo.


basal ring of apical complex

description: An electron dense ring at the most posterior position of the apical complex, from which the subpellicular microtubules originate; formed during an invasive life cycle stage of an apicomplexan parasite.


chromoplast intermembrane space

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


basal pole of neuron

description: Portion of a neuron cell soma closest to the point where the basilar dendrite emerges.


rough endoplasmic reticulum cisterna

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


name: mitotic actomyosin contractile ring, distal actin filament layer

description: The region of the mitotic actomyosin ring containing actin filaments and cross linkers, myosin motors, and connections to the plasma membrane through the intermediate layer. It is further from the plasma membrane than the intermediate layer which it is adjacent to.


organelle envelope lumen

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


centrosomal corona

description: An amorphous structure surrounding the core of the centrosome, from which microtubules are nucleated; contains gamma-tubulin.


dendritic branch point

description: The part of a dendritic tree where it branches, giving rise to a dendritic branch.


upper tip-link density

description: An electron-dense plaque at the upper end of a stereocilia tip link that provides the anchor in the stereocilia membrane on the side of the stereocilium where the tip link ends.


fungal-type vacuole lumen

description: The volume enclosed within the vacuolar membrane of a vacuole, the shape of which correlates with cell cycle phase. An example of this structure is found in Saccharomyces cerevisiae.


name: prospore membrane spindle pole body attachment site

description: The region of the prospore membrane to which the spindle pole body (SPB) is anchored; the prospore membrane extends from the SPB attachment site to surround the spore nucleus.


right middle basal body pair

description: Set of two basal bodies found in Giardia species (trophozoite stage). It comprises the caudal and posteriolateral basal bodies located to the left of the right nucleus of the trophozoite when viewed dorsally.


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

description: The fluid-filled cuticle layer that lies between the cortical and basal layers and is characterized by the presence of regularly spaced columnar struts that lie on either side of the annular furrows and link the two surrounding layers. In C. elegans, a defined medial layer is found only in adult animals.


late endosome lumen

description: The volume enclosed by the membrane of a late endosome.


apical pole of neuron

description: Portion of a neuron cell soma closest to the point where the apical dendrite emerges.


cytoskeletal calyx

description: A large cytoskeletal structure located at the posterior end of the perinuclear theca of a mammalian sperm head. The nucleus is tightly associated with the calyx, which contains calicin and basic cylicin proteins.


host cell presynaptic membrane

description: A specialized area of membrane of the host axon terminal that faces the plasma membrane of the host neuron or muscle fiber with which the axon terminal establishes a synaptic junction; many host synaptic junctions exhibit structural presynaptic characteristics, such as conical, electron-dense internal protrusions, that distinguish it from the remainder of the axon plasma membrane.


somatic ring canal

description: A stable intercellular bridge between somatic cells. Examples include the intercellular bridges between ovarian follicle cells in insects and between imaginal disc cells in insects.


type III 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. Type III terminal boutons are larger than type II ones.


distal axon

description: That part of an axon close to and including the growth cone or the axon terminus.


bacterial extracellular vesicle

description: Small membrane vesicle (< 1 um) that buds off a prokaryotic cell plasma membrane, able to carry proteins, phospholipids, lipopolysaccharides, nucleic acids, viruses, and more. Important in intercellular communication and pathogenesis; can exist within host cells.


dinoflagellate antapical horn

description: A horn-shaped dinoflagellate antapex found in thecate species.


name: epicuticle of collagen and cuticulin-based cuticle extracellular matrix

description: A lipid-containing layer of cuticle that lies between the cortical layer and the surface coat. An example of this component is found in Caenorhabditis elegans.


muscle cell postsynaptic specialization

description: A postsynaptic specialization that is part of a neuromuscular junction.


right lateral basal body pair

description: Set of two basal bodies found in Giardia species (trophozoite stage). It comprises the anterior and ventral basal bodies located to the left of the right nucleus of the trophozoite when viewed dorsally.


sperm individualization complex

description: A cellular structure that includes cytoskeletal components and part of the cell membrane. Forms at the nuclear end of a male germline syncytium, or cyst, and translocates the over the length of the syncytium in the course of sperm individualization. Each complex contains an array of 64 investment cones, one per nucleus, that move synchronously along the spermatogenic cyst.


chloroplast thylakoid lumen

description: The cavity enclosed within the chloroplast thylakoid membrane. An example of this component is found in Arabidopsis thaliana.


meiotic spindle midzone

description: The area in the center of the meiotic spindle where the spindle microtubules from opposite poles overlap.


endoplasmic reticulum exit site

description: An endoplasmic reticulum part at which COPII-coated vesicles are produced.


cell envelope

description: An envelope that surrounds a bacterial cell and includes the cytoplasmic membrane and everything external, encompassing the periplasmic space, cell wall, and outer membrane if present.


curli

description: A proteinaceous extracellular fiber, produced by an enteric bacterium, that is involved in surface and cell-cell contacts that promote community behavior and host colonization.


actin rod

description: A cellular structure consisting of parallel, hexagonally arranged actin tubules, comprising filamentous actin and associated proteins. Actin rod structures are found in diverse organisms, having been observed in spores of Dictyostelium discoideum, Drosophila melanogaster oocytes, as well as in numerous animal cells under stress conditions.


name: nucleoplasmic periphery of the nuclear pore complex

description: Nucleoplasm situated in close proximity and peripheral to a nuclear pore complex.


plastid inner membrane

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


intracellular canaliculus

description: An apical plasma membrane part that forms a narrow enfolded luminal membrane channel, lined with numerous microvilli, that appears to extend into the cytoplasm of the cell. A specialized network of intracellular canaliculi is a characteristic feature of parietal cells of the gastric mucosa in vertebrates.


organelle subcompartment

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


name: cellularization cleavage furrow invagination front

description: The base of the cellularization invagination or cleavage furrow most distal to the original multi-nucleate cell or syncytium plasma membrane.


dendritic shaft

description: Cylindric portion of the dendrite, directly stemming from the perikaryon, and carrying the dendritic spines.


plasma membrane region

description: A membrane that is a (regional) part of the plasma membrane.


photoreceptor disc membrane

description: Stack of disc membranes located inside a photoreceptor outer segment, and containing densely packed molecules of photoreceptor proteins that traverse the lipid bilayer. Disc membranes arise as evaginations of the ciliary membrane during the development of the outer segment and may or may not remain contiguous with the ciliary membrane.


perinuclear endoplasmic reticulum

description: The portion of endoplasmic reticulum, the intracellular network of tubules and cisternae, that occurs near the nucleus. The lumen of the perinuclear endoplasmic reticulum is contiguous with the nuclear envelope lumen (also called perinuclear space), the region between the inner and outer nuclear membranes.


suberin network

description: An extracellular matrix part that consists of fatty acid-derived polymers, including both aromatic and aliphatic components. The suberin network is found in specialized plant cell walls, where it is laid down between the primary wall and plasma membrane, forms protective and wound-healing layers, and provides a water-impermeable diffusion barrier.


elaioplast stroma

description: The space enclosed by the double membrane of an elaioplast.


perikaryon

description: The portion of the cell soma (neuronal cell body) that excludes the nucleus.


prospore contractile ring

description: A contractile ring, i.e. a cytoskeletal structure composed of actin filaments and myosin, that forms beneath the plasma membrane of the prospore envelope in meiotic cells in preparation for completing cytokinesis.


myelin sheath abaxonal region

description: The region of the myelin sheath furthest from the axon.


mesosome

description: An intracellular, often complex, membranous structure, sometimes with additional membranous lamellae inside, found in bacteria. They are associated with synthesis of DNA and secretion of proteins.


germ cell nucleus

description: The nucleus of a germ cell, a reproductive cell in multicellular organisms.


filopodium membrane

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


septin band

description: A diffuse ring composed of a series of septin bars that run parallel to the long axis of the cell. This type of septin structure has been observed in a number of locations associated with polarized grown and/or deposition of new membrane, but not with cytokinesis, such as at the shmoo (mating projection) neck, at the junction between the mother cell and the germ tube (hypha) of a fungal cell growing filamentously.


name: bacterial-type flagellum basal body, C ring

description: Cytoplasmic ring located at the base of the bacterial-type flagellar basal body; acts as a rotor; includes three switch proteins, which generate torque and can change their conformational state in a bimodal fashion, so that the motor direction can switch between clockwise and counterclockwise.


name: extrinsic component of thylakoid membrane

description: The component of a thylakoid membrane consisting of gene products and protein complexes that are loosely bound to one of its surfaces, but not integrated into the hydrophobic region.


membrane-enclosed lumen

description: The enclosed volume within a sealed membrane or between two sealed membranes. Encompasses the volume enclosed by the membranes of a particular organelle, e.g. endoplasmic reticulum lumen, or the space between the two lipid bilayers of a double membrane surrounding an organelle, e.g. nuclear envelope lumen.


cyst wall

description: The specialized envelope lying outside the cell membrane of a cyst. A cyst is a resting or dormant stage of a microorganism, usually a bacterium or a protist or rarely an invertebrate animal, that helps the organism to survive in unfavorable environmental conditions. In protists such as protozoan parasites alternating cystic- and non-cystic stages, the cyst wall is usually composed of carbohydrates and proteins.


stereocilium membrane

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


inner membrane pellicle complex

description: A membrane structure formed of two closely aligned lipid bilayers that lie beneath the plasma membrane and form part of the pellicle surrounding an apicomplexan parasite cell.


orthogonal array

description: Square array of closely spaced intramembrane particles, 4-6 nm in size, that form supramolecular aggregates found in the plasma membrane of astrocytes, skeletal muscle and epithelial cells. They have been shown to contain aquaporins (water channels).


endospore cortex

description: A layer surrounding a bacterial endospore found inside the outer endospore membrane, but outside the membrane surrounding the endospore core. It consists of peptidoglycan of a different chemical nature than that found in vegetative cell walls which results in less cross-linking of peptidoglycan.


name: half bridge of mitotic spindle pole body

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


post-anaphase microtubule array

description: A cytoskeletal part that consists of an array of microtubules and associated molecules that forms at the end of anaphase, and in which microtubules are nucleated from an equatorial microtubule organizing center.


node of Ranvier

description: An axon part that is a gap in the myelin where voltage-gated sodium channels cluster and saltatory conduction is executed.


gas vesicle shell

description: The proteinaceous structure surrounding a gas vesicle.


root hair tip

description: The tip portion of an outgrowth of a root epidermal cell.


anammoxosome

description: An intracytoplasmic membrane-bounded compartment in anaerobic ammonium oxidation (anammox) bacteria, is the site of anammox catabolism.


P4 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. P4 peroxisomes are distinguished from the other subforms on the bases of buoyant density and protein content.


name: outer plaque of mitotic spindle pole body

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


extracellular organelle

description: Organized structure of distinctive morphology and function, occurring outside the cell. Includes, for example, extracellular membrane vesicles (EMVs) and the cellulosomes of anaerobic bacteria and fungi.


unicellular trichome apex

description: A cell projection part that is the apical most portion of a unicellular trichome.


lateral shield

description: Region of the ventral side of the cell body found in Giardia species (trophozoite stage). It is located posterior on either side of the ventral groove; the upper boundary is the ventral disc, and the lower boundary is marked by the posteriolateral flagella.


plasma membrane-derived chromatophore

description: A pigment-bearing structure that is derived from the cytoplasmic membrane, sometimes consisting of simple invaginations and sometimes a complete vesicle. This component is found in certain photosynthetic bacteria and cyanobacteria.


organelle envelope

description: A double membrane structure enclosing an organelle, including two lipid bilayers and the region between them. In some cases, an organelle envelope may have more than two membranes.


cell projection membrane

description: The portion of the plasma membrane surrounding a plasma membrane bounded cell surface projection.


ascus membrane

description: A double layer of lipid molecules that surrounds an ascus, a capsule containing the sexual spores in some fungi.


synaptic membrane

description: A specialized area of membrane on either the presynaptic or the postsynaptic side of a synapse, the junction between a nerve fiber of one neuron and another neuron or muscle fiber or glial cell.


endoplasmic reticulum tubular network

description: A subcompartment of the endoplasmic reticulum consisting of tubules having membranes with high curvature in cross-section.


brush border membrane

description: The portion of the plasma membrane surrounding the brush border.


spine apparatus membrane

description: The lipid bilayer surrounding the spine apparatus.


synaptonemal structure

description: A proteinaceous scaffold found between homologous chromosomes during meiosis.


old growing cell tip

description: A cell tip which has existed for at least one complete cell cycle, and at which polarized growth occurs. For example, in fission yeast the cell end that existed prior to cell division grows immediately after division, and contains a distinctive complement of proteins including actin cytoskeletal structures.


ciliary tip

description: Part of the cilium where the axoneme ends. The ciliary tip has been implicated in ciliary assembly and disassembly, as well as signal transduction.


intine

description: The innermost of the major layers of the pollen grain wall which underlies the exine and borders the cytoplasm.


microsporidian-type exospore

description: The dense, protein rich outermost layer of a microsporidian spore wall that lies above the endospore.


sarcoplasmic reticulum lumen

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


clathrin-coated pit

description: A part of the endomembrane system in the form of an invagination of a membrane upon which a clathrin coat forms, and that can be converted by vesicle budding into a clathrin-coated vesicle. Coated pits form on the plasma membrane, where they are involved in receptor-mediated selective transport of many proteins and other macromolecules across the cell membrane, in the trans-Golgi network, and on some endosomes.


rDNA protrusion

description: Any of the tandem arrays of rDNA localized at the periphery of the nucleus and protruding into the nucleolus, and associated proteins. May be visible as a single or double spot by DAPI staining.


microneme lumen

description: The volume enclosed by the microneme membrane.


Casparian strip

description: Region of plant cell wall specialised to act as a seal to prevent back leakage of secreted material (analogous to tight junction between epithelial cells). Found particularly where root parenchymal cells secrete solutes into xylem vessels. The barrier is composed of suberin; a fatty substance, containing long chain fatty acids and fatty esters, also found in the cell walls of cork cells (phellem) in higher plants.


rhoptry neck

description: Narrow, electron-dense part of the rhoptry that extends through the conoid at the apical tip of an apicomplexan parasite. The rhoptry neck serves as a duct through which the contents of the rhoptry are secreted after attachment to the host has been completed and at the commencement of invasion.


GABA-ergic synapse

description: A synapse that uses GABA as a neurotransmitter. These synapses are typically inhibitory.


podosome core

description: The F-actin-rich core of an adhesion structure characterized by formation upon cell substrate contact and localization at the substrate-attached part of the cell.


nuclear envelope

description: The double lipid bilayer enclosing the nucleus and separating its contents from the rest of the cytoplasm; includes the intermembrane space, a gap of width 20-40 nm (also called the perinuclear space).


exine

description: The outer layer of the pollen grain wall which is composed primarily of sporopollenin.


inhibitory synapse

description: A synapse in which an action potential in the presynaptic cell reduces the probability of an action potential occurring in the postsynaptic cell.


amphisome

description: Intermediate organelles formed during macroautophagy through the fusion between autophagosomes and endosomes.


magnetosome membrane

description: The lipid bilayer surrounding a magnetosome.


phagophore

description: A disk-like structure that expands, rounds up into a cup-shaped structure, and eventually closes around its cargo (for example cytoplasmic components) to become an autophagosome or Cvt vesicle.


conoid

description: A spiral cytoskeletal structure located at the apical end of the apical complex in some apicomplexan parasites. Fibers form a left-handed spiral, and are comprised of tubulin protofilaments organized in a ribbon-like structure that differs from the conventional tubular structure characteristic of microtubules.


polar ring of apical complex

description: An electron dense ring at the most anterior position of the apical complex, from which the conoid fibers originate; formed during an invasive life cycle stage of an apicomplexan parasite.


hydrogenosomal membrane

description: The lipid bilayer surrounding a hydrogenosome.


cleavage furrow leading edge

description: The 'trough' of the cleavage furrow. This is the part of the cleavage furrow closest to the contractile ring.


external side of fungal-type cell wall

description: The side of the fungal-type cell wall that is opposite to the side that faces the cell and its contents.


growing cell tip

description: The region at either end of the longest axis of a cylindrical or elongated cell, where polarized growth occurs.


name: axonemal microtubule doublet inner junction

description: The structure which joins the B10 protofilament of the B tubule to the A1 protofilament of the A tubule within an axonemal microtubule doublet.


mitosome

description: A double-membrane-bounded organelle that functions in iron-sulfur protein maturation; evolutionarily derived from mitochondria. The mitosome has been detected only in anaerobic or microaerophilic organisms that do not have mitochondria, such as Entamoeba histolytica, Giardia intestinalis and several species of Microsporidia. These organisms are not capable of gaining energy from oxidative phosphorylation, which is normally performed by mitochondria.


bilobe structure

description: A cytoskeletal structure in some kinetoplastid species linking the structures of the ciliary pocket collar and the flagellum attachment zone (aka cilium attachment zone).


actin filament branch point

description: The part of an actin filament where the structure forks.


hydrogenosome

description: A spherical, membrane-bounded organelle found in some anaerobic protozoa, which participates in ATP and molecular hydrogen formation.


symbiont-containing vacuolar space

description: The space between a symbiont plasma membrane and the symbiont-containing vacuole membrane.


endonuclear canal

description: A membrane-bound structure present in the nucleus of a spermatozoon. There is variation in the number of endonuclear canals between sperm of different organisms, and some species lack these structures altogether. The endonuclear canal may provide a supporting role for the sperm nucleus, and originates during spermiogenesis from an invagination of the nuclear envelope.


endothelial microparticle

description: A blood microparticle that is derived from, and contains membrane receptors as well as other proteins characteristic of, an endothelial cell.


name: presynaptic active zone dense projection

description: Electron dense projection extending from the cytomatrix into the cytoplasm on which synaptic vesicles are tethered.


acrosomal matrix

description: A structural framework, or 'dense core' at the interior of an acrosome. May regulate the distribution of hydrolases within the acrosome and their release during the acrosome reaction.


actomyosin contractile ring

description: A cytoskeletal structure composed of actin filaments and myosin that forms beneath the plasma membrane of many cells, including animal cells and yeast cells, in a plane perpendicular to the axis of the spindle, i.e. the cell division plane. In animal cells, the contractile ring is located at the cleavage furrow. In budding fungal cells, e.g. mitotic S. cerevisiae cells, the contractile ring forms at the mother-bud neck before mitosis.


etioplast prolamellar body

description: A three dimensional regular lattice found in etioplasts. It is composed of a continuous system of tubules but when exposed to light the symmetrical arrangement is rapidly lost as tubules become pinched off into two dimensional sections of lattice. These for perforated sheets of membrane that move apart, extend and increase, finally establishing the typical granal and intergranal lamellae of the mature chloroplast.


Hechtian strand

description: An extended membranous thread which firmly connects the plasma membrane to the cell wall during plasmolysis such that the plasma membrane does not separate from the cell wall completely.


platelet dense tubular network lumen

description: The volume enclosed by the membranes of the platelet dense tubular network.


Golgi lumen

description: The volume enclosed by the membranes of any cisterna or subcompartment of the Golgi apparatus, including the cis- and trans-Golgi networks.


cytostome

description: Stable, specialized structure for the ingestion of food by the cell into phagosomes.


endosperm protein body

description: A membrane-bounded plant organelle found in the developing endosperm, contains storage proteins.


name: bacterial-type flagellum basal body, distal rod, P ring

description: One of the rings of the bacterial-type flagellar basal body; anchors the basal body to the peptidoglycan layer.


transverse filament

description: A structural unit of the synaptonemal complex that spans the regions between the lateral elements and connects them.


prominosome

description: An extracellular membrane-bounded vesicle that contains prominin proteins (in mouse Prom1/CD33 or Prom2) and are found in body fluids including ventricular fluid, saliva, urine and seminal fluid. In the ventricular fluid of the developing mouse brain two major classes of these particles have been observed (P2 particles of 500-1000 nm and P4 particles of 50-80 nm) which likely originate from microvilli, primary cilia and/or the midbody of neuroepithelial cells. The physiological role is not known.


name: extrinsic component of external side of cell outer membrane

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


bacterial biofilm matrix surface

description: The external part of the biofilm matrix, a structure lying external to bacterial cells. A biofilm is an aggregate of surface-associated bacteria, and the biofilm matrix is the envelope of polymeric substances that surrounds the bacteria.


extrachromosomal circular DNA

description: Circular DNA structures that are not part of a chromosome.


adventitious septum

description: A cell septum whose formation is independent of nuclear division.


sperm annulus

description: The ring-like, filamentous structure located at the distal end of the midpiece of the sperm flagellum; the annulus is thought to form a diffusion barrier between the midpiece and the principal piece and serve as a stabilizing structure for tail rigidity.


mesoderm-derived structure

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

description: An anatomical structure that develops (entirely or partially) from the mesoderm.


chemical entity

A chemical entity is a physical entity of interest in chemistry including molecular entities, parts thereof, and chemical substances.


main group molecular entity

A molecular entity containing one or more atoms from any of groups 1, 2, 13, 14, 15, 16, 17, and 18 of the periodic table.


virus tail, baseplate

description: Multiprotein component at the distal (head) end of the virus tail to which fibers of tailed viruses may be attached.


polyatomic entity

Any molecular entity consisting of more than one atom.


virus tail, tip

description: The basal end of the virus tail, which is used by the virus to attach to the host cell.


virus tail

description: Part of the virion that may be used to recognize, attach and inject the viral genome and accessory proteins into the host cell.


virus tail, tube

description: The internal tube of the contractile tails of some viruses. The virus tail tube is the channel for DNA ejection into the host cytoplasm.


icosahedral viral capsid, collar

description: A small disk located at the base of some icosahedral virus capsids.


icosahedral viral capsid, neck

description: A region of constriction located below the head and above the tail sheath of viruses with contractile tails (Myoviridae).


virus tail, shaft

description: The tube of the non-contractile tails of some viruses.


molecular entity

Any constitutionally or isotopically distinct atom, molecule, ion, ion pair, radical, radical ion, complex, conformer etc., identifiable as a separately distinguishable entity.