A B C D E F G H I J K L M N O P Q R S T U V W X Y Z 

Glossary - V






Ventrolateral ectoblasts of the body that give rise to neurons, hypodermis and seam cells.

VA cells


A set of 12 motoneurons, distributed along the ventral cord, that innervate ventral body muscles.

VB cells


A set of 11 motoneurons, distributed along the ventral cord, that innervate ventral body muscles.

VC cells


A set of 6 motoneurons in the ventral cord, that innervate ventral body muscles and the vm2 muscles of the vulva.

VD cells


A set of 13 motoneurons, with cell bodies in the ventral cord, that innervate ventral muscles.



A large membrane-bound organelle within the cell cytoplasm. This term may sometimes be used in reference to distinctive large endosomes in the intestine, the primary oocyte, or in some sheath cells.

More properly, it can be used to refer to an extremely large internal compartment that develops in the embryonic excretory canal cell (and perhaps the excretory duct cell) as a precursor to the excretory sinus and apical excretory canal (Buechner, 2002; Berry et al., 2003) that shows enhanced membrane density compared to any other internal organelles.

Vacuoles are often found in cell that are involved in the storage of material such as secretory cells and coelomocytes.

Vacuoles and vacuole-like structures have been noted as features of apoptotic and necrotic cell death.

Vagina Vulva (S)

Alternate (archaic) term used by some authors for the vulva (Klass et al., 1976; Riddle, 1978).


A device that regulates the flow of liquids. In C. elegans valve and valve-like structures have been identified, usually connecting two tissues through which material is being shunted.

The pharyngeal-intestinal valve links the lumen from the posterior bulb of the pharynx to the lumen of the anterior intestine. The intestinal-rectal (rectal) valve occludes the lumen of the posterior intestine with narrow channels that allow digested material to leak to the rectum and then to the anus. It is not clear that this is a true valve since it is unknown whether the size and state of the opening can be altered. The spermatheca-uterine (sp-ut) valve connects the spermatheca to the uterus for the passage of the oocyte and seals the lumen when empty.

The anterior end of the vas deferens may act as a kind of valve to regulate sperm release from the seminal vesicle during ejaculation.

Even the pharyngeal grinder is considered a valve by some authors (Nicholas, 1975).

See Pharyngeal-intestinal valve
See Rectal valve
See Spermatheca uterine valve
See Vas deferens


A local swelling of a tissue or cell process, especially at the presynaptic site which can be full of synaptic vesicles.

Vas deferens Sperm duct (S)  

That portion of the male reproductive tract, through which mature sperm are delivered to the proctodeum and then the cloaca in the tail. It is composed of 30 cells which form three distinct sections within the tissue. The anterior region appears to act as a valve to regulate sperm release during ejaculation. The middle portion is composed of cuboidal cells, while in the most posterior region the cells are elongated.


A thin membranous tissue part or covering; sometimes used in reference to the male tail fan.

Ventral aspect Ventral view (S)

Looking toward the underside or belly of the animal.

Ventral bend


See Deep ventral bend

Ventral cleft Ventral groove (S)

A region along the ventral side of the gastrulating embryo through which blast cells migrate inward from the surface layer of embryonic cells to a central collection of developing mesoderm and pharynx. The cleft opens as a pore at 100 minutes after fertilization (60 cell stage), widens to form a cleft from posterior to anterior along the ventral side, and closes at 290 minutes (~320 cells).

See Gastrulation

Ventral cord Ventral chord (S)  

This term can refer to either the ventral nerve cord, to the hypodermal cord, or to the combined ventral ridge of hypodermis and nerve.

The ventral hypodermis forms a rather small longitudinal cord and contains few hypodermal nuclei. It is a syncytium and connects to much larger lateral cords via thin extensions running beneath the bodywall muscles.

The ventral nerve cord is the principal longitudinal nerve of the midbody region, connecting the nerve ring and tail ganglia. It contains about 95 associated neuron cell bodies of the principal motorneurons that control the bodywall muscles, and many synapses sending signals from command interneurons to these motorneurons and then to muscle arms.

See Nerve cord
See Hypodermal ridge

Ventral enclosure Ventral cleft closure (S)  

See Ventral cleft

Ventral ganglion    

The ventral ganglion lies beside the nerve ring in the head, just anterior of the retrovesicular ganglion. It contains about 20 interneuron and motorneuron cell bodies that all send their neuronal processes into the ring. The cell bodies are divided into two groups by the intrusion of the excretory duct and canal. The cells are bounded by a basal lamina which physically separates them from the lateral ganglion even though they are adjacent to one another.

Ventral groove Ventral cleft (S)


Ventral midline  

In transverse section, the ventral midline runs through the middle of the ventral hypodermal ridge, along the dorsal/ventral axis, separating the left and right halves of the ventral bodywall. It is a key feature in the organization of longitudinal ventral nerve cord, which divides into two separate fascicles that run preferentially to the right side (major fascicle) and left side (minor fascicle) of the hypodermal ridge.

See Decussation
See Hypodermal ridge

Ventral nerve cord

Ventral cord (S)


Ventral ray

Any ray in the male tail whose opening lies on the ventral surface of the fan. The pattern of these opening is highly stereotyped, such that certain rays always open dorsally (1, 5 and 7), others ventrally (2, 4 and 8), and a few at the lateral margin of the fan.

Ventral twelve    

See VT1-VT12

Ventral uterus    

Thirty cells (15 per gonad arm) derive from variable lineages among sister cells to the anchor cell in the gonad primordium, all of which contribute to the more ventral aspects of the uterine epithelium.

See Doral uterus
See VU cell

Ventral uterine precursor

VU cell (S)


Each VU blast cell undergoes two rounds of cell divisions to produce pi cells and/or ro cells, depending upon induction by a signal from the anchor cell. These intermediate blast cells then go on to divide further to produce the uv and utse cells of the ventral uterus.

See Anchor cell
See Dorsal uterus

Ventral view

Ventral aspect (S)

Ventricular zone    

Anterior portion of intestine.

See Intestine


Worm-like. This term can be used to refer to whole animals, or to body parts that have features like a worm. In human anatomy, this term is used to describe the appendix.



A number of different cell types contain characteristic membrane-bound vesicles.

Transitory vesicles appear in the excretory canal upon breakdown of the canaliculi, which appear to convert from a beaded form to a row of disconnected vesicles.

Endocytotic vesicles (>100 nm diameter) are found in coelomocytes, the distal tip cell, the GLR cells and the intestine.

Secretory vesicles are found in several gland cells and all neurons.

Transport vesicles may shuttle between RERsmooth ER, Golgi apparatus, endosomal structures and the plasma membrane; these are perhaps more common in secretory cells and in neurons.

See Synaptic vesicle
See Coated vesicle
See Dense core vesicle

Vesicle docking    

This step in the synaptic vesicle cycle is not well documented, but refers to the process by which a vesicle identifies, approaches and becomes associated with the plasma membrane near the active zone of the synapse prior to priming (Richmond, 2005). It is thought that this may be a reversible stage in the vesicle cycle.

Vesicle fusion    

This is a specific step in the synaptic vesicle cycle where the synaptic vesicle fuses with the plasma membrane and releases neurotransmitter into the synaptic cleft (Richmond, 2005; Speese et al., 2007).

More generally, this can refer to the fusion of any type of vesicle with another membrane bound system to release its contents. During this process, an omega figure is often formed as an intermediate stage. For more detail on mechanism see Podbilewicz, 2006.

See Fusion

Vesicle priming    

This step in the synaptic vesicle cycle follows vesicle docking and makes the vesicle competent for fusion by brining the vesicle into close apposition with the plasma membrane (Richmond, 2005). The vesicle then waits for a rise in intracellular calcium to fuse with the membrane and release its contents.



Anatomical structures which have lost much (or all) of their original function through evolution. Sometimes these structures may develop new functions different from their original ones.



Ability to survive and develop.

Villus/ Villi  

A large fold or projection in the apical membrane of any tissue with a mucous membrane. It is not clear that this term applies to any structure in C. elegans.

While the intestinal lumen displays a brush border with many “microvilli”, it is not clear that it has any "villi". The border of the excretory canal where it faces the lumen can display cystic septations, but rarely if ever has true villi. The finger-like projections of the AFD dendrite might be considered villi or microvilli.

See Brush border
See Finger-like projections
See Finger cell
See Microvilli

Virulence/ Virulent/ Virulence factor  

The degree of pathogenicity of a microbe.

Virulence factor  

A substance or genetic trait that affects the rate of host/pathogen interaction to increase the rate of infection or killing.

See Killing assay



C. elegans lacks an eyespot and has no ability to see, it has been reported to exhibit a response to light (Burr, 1985; Ken Miller, pers. comm.).

See Eyespot

Vitelline layer


The outermost layer of the eggshell [according to most nematology literature], lying very closely attached to the outside of the chitinous layer. It may be hardened or not and it may have a unit membrane structure or not (see Bird and Bird, 1991). This layer is not well documented for C. elegans, and the nomenclature is confused, since the internal “lipid layer” has been incorrectly named the inner vitelline membrane in many papers. Some or all of the outer vitelline layer may derive from secretions from the uterine epithelium.

Vitelline membrane

Inner vitelline membrane (S)
Lipid layer (S)
Vitelline envelope (S)

Formerly called the “lipid layer” (Bird, 1971), it is a very thin lipid layer surrounding the developing embryo, just beneath the outer chitinous layer of the eggshell. This membrane must be kept intact to establish a microenvironment within which the embryo can develop properly (Schierenberg and Junkersdorf, 1992). Although not clearly established as yet, it is possible that this layer is contributed to the oocyte by the uterine sheath.

See Oolemma
See Zona pellucida

Vitellogenin Yolk protein (S)

See Yolk

VL neuron

Ventro-labial neuron

OLL neuron

VM neuron


RMEL neuron


Vulval precursor cell


An epidermal cell which can be induced to produce vulval tissue. The VPCs are equivalent blast cells P3.p, P4.p, P5.p, P6.p, P7.p and P8.p which can alternately be induced by an anchor cell signal to divide to produce vulA to vulF epidermal cells or (lacking the inductive signal) divide to produce members of the hyp7 syncytium.

VT1-VT12 Ventral twelve (S)  

Great-grand progeny of the VU cells (daughters of the π and ρ cells) in the uterine lineages.

VU cell Ventral uterine precursor (S)  

Blast cells in the somatic gonad whose granddaughter cells can give rise to both vulval and uterine cells, depending upon intracellular signals.


See Vulvaless phenotype

vulA, vulB1, vulB2, vulC, vulD, vulE, vulF


Seven epithelial syncytia (toroids) that encircle the vulval passageway in segmental fashion, produced by the fusions of some 22 larval cells, the vulval equivalence group (Shemer and Podbilewicz, 2000; Podbilewicz, 2006). The outermost toroid is called vulA, connecting to the vulval lips, and the innermost toroid is called vulF, connecting to the uterus.

See Toroidal cells

Vulva Vagina (S) Terminal female gonoduct (S) Gonopore (S)  

The passageway that connects the hermaphrodite’s reproductive tract to the exterior, opening at the midway point along the body on its ventral surface. The vulva is formed from a stack of 7 toroids which upon morphogenesis undergo cell fusion to create an open lumen. During male mating, sperm are inserted into the hermaphrodite through the vulval passageway, whereas during egg-laying, fertilized oocytes are emitted onto the substrate from the vulva through the slit.

Vulval epithelium



A narrow epithelial tube that lines the opening of the reproductive tract on the ventral surface of the hermaphrodite, covered by a set of ring-shaped syncytial cells that cover sequential segments of the tube. The epithelial cells lie only one cell deep, and form a cuticle lined passageway to the uterus. Two pairs of vulval muscles are anchored to these epithelial cells in order to open the vulval lips and the passageway during egg-laying.

Vulval equivalence group  

A set of 22 cells, normally formed by the daughters of the P5.p, P6.p and P7.p blast cells, which are fated to organize among themselves to create the mature vulval epithelium and are induced to adopt this set of cell fates by a signal produced by the anchor cell (Sulston and White, 1980; Sommer, 2005, Gupta et al., 2012). The pattern of cell divisions among the blast cells is controlled separately from the cooperation that occurs later among the daughter cells during the L4 stage to produce the vulva (Horvitz and Sulston, 1980). If some of these cells are removed by ablation 10-12 hrs before hatching, additional cells can be recruited from the daughters of neighboring blast cells, P3.p, P4.p or P8.p in order to complete the set of 22 cells and thus produce a normal vulva.

See Equivalence group
See Toroidal cells

Vulval induction  

An intercellular signaling event by which members of the vulval equivalence group are provoked to begin the processes of differentiation and cell division that lead to the creation of the vulva. This process can differ widely between nematode species, such that one or several inductive signals may be released by one or more cell types lying close to the position of the presumptive vulva, and can occur as a one time event or as a prolonged series of signals (Sommer, 2005). In C. elegans, the anchor cell provides the inductive signal that triggers this patterning event. See Sternberg, 2005 and Gupta et al., 2012.

See Anchor cell

Vulvaless phenotype vul  

A developmental defect found in certain classes of mutants (including lin-2, lin-3, lin-4, lin-7) in which the cell divisions leading to vulva development are abnormal, and the vulval cells are not produced (Horvitz and Sulston, 1980; Sulston and Horvitz, 1981). Without a passageway for the fertilized embryos, the embryos hatch inside the hermaphrodite, resulting in a bag of worms.

See Bag of worms
See Multivulva phenotype

Vulval location

Vulval searching (S)


A type of behavior by the male in which he uses his tail  to guide his movements along the outer surface of the hermaphrodite to search for the vulva as an early step in male mating behavior.

Vulval muscle vm muscles (S)
vm1 and vm2 (S)

Sex-specific muscles in the hermaphrodite that are specialized for egg-laying. Their contractions open the lips of the vulva to help in expelling an egg from the uterus.

Vulval precursor cell



Edited for the web by Laura A. Herndon. Last revision: October 16, 2013. This section should be cited as: Herndon, L.A. and Hall, D.H. 2010. Glossary V. In WormAtlas.  doi:10.3908/wormatlas.6.22