muscle cell postsynaptic specialization

A postsynaptic specialization that is part of a neuromuscular junction.


right lateral basal body pair

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

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

A macromolecular complex 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

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


meiotic spindle midzone

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


endoplasmic reticulum exit site

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


cell envelope

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

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

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.


nucleoplasmic periphery of the nuclear pore complex

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


plastid inner membrane

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


intracellular canaliculus

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

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


cellularization cleavage furrow invagination front

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


dendritic shaft

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


plasma membrane region

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


photoreceptor disc membrane

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

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

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

The space enclosed by the double membrane of an elaioplast.


perikaryon

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


plant-type vacuole membrane

The lipid bilayer surrounding a vacuole that retains the same shape regardless of cell cycle phase. The membrane separates its contents from the cytoplasm of the cell. An example of this component is found in Arabidopsis thaliana.


prospore contractile ring

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

The region of the myelin sheath furthest from the axon.


mesosome

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

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


filopodium membrane

The portion of the plasma membrane surrounding a filopodium.


septin band

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.


bacterial-type flagellum basal body, C ring

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.


extrinsic component of thylakoid membrane

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

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

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

The portion of the plasma membrane surrounding a stereocilium.


inner membrane pellicle complex

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

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

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.


half bridge of mitotic spindle pole body

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


post-anaphase microtubule array

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

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


cell surface

The external part of the cell wall and/or plasma membrane.


gas vesicle shell

The proteinaceous structure surrounding a gas vesicle.


root hair tip

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


anammoxosome

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


P4 peroxisome

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.


outer plaque of mitotic spindle pole body

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


extracellular organelle

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

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


lateral shield

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

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

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

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


ascus membrane

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


synaptic membrane

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

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


spine apparatus membrane

The lipid bilayer surrounding the spine apparatus.


synaptonemal structure

A proteinaceous scaffold found between homologous chromosomes during meiosis.


old growing cell tip

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

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

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


cellular bud neck

The constriction between the mother cell and daughter cell (bud) in an organism that reproduces by budding.


microsporidian-type exospore

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


sarcoplasmic reticulum lumen

The volume enclosed by the membranes of the sarcoplasmic reticulum.


clathrin-coated pit

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

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

The volume enclosed by the microneme membrane.


Casparian strip

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

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

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


podosome core

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

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

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


inhibitory synapse

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


amphisome

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


magnetosome membrane

The lipid bilayer surrounding a magnetosome.


phagophore

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

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

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

The lipid bilayer surrounding a hydrogenosome.


cleavage furrow leading edge

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

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


growing cell tip

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


mitosome

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

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

The part of an actin filament where the structure forks.


hydrogenosome

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


symbiont-containing vacuolar space

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


endonuclear canal

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

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


presynaptic active zone dense projection

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


acrosomal matrix

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

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

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

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

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


Golgi lumen

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


cytostome

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


endosperm protein body

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


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

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


transverse filament

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


prominosome

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.


extrinsic component of external side of cell outer membrane

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

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

Circular DNA structures that are not part of a chromosome.


adventitious septum

A cell septum whose formation is independent of nuclear division.


sperm annulus

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

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

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

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

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


virus tail

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

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

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


icosahedral viral capsid, neck

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


virus tail, shaft

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.