ABBREVIATION

SYNONYMS (S)
ANTONYMS (A)

Somatic blastomeres

The original nomenclature of Boveri (1899) for the early cell divisions of the nematode embryo. S1 is now called AB, S2 is now EMS, S3 is C, and S4 is D.

Sagittal sections run from one side of the body to the other (left to right or vice versa) following the sagittal plane (Y-Z axis) that divides the body into right and left portions and is parallel to the median plane.

A characteristic jerky motion involving abrupt transitions between motion and immobility. Motions of a certain speed continue for short duration, alternating with periods of immobility. Such dynamics are typical of some objects under the control of molecular motors, whose activity may rapidly switch between ON and OFF states as is during axonal transport of dense core vesicles (Zhan et al., 2004).

Also can be used to describe the evolutionary theory that reveals discontinuous, large jumps in the evolution of a species (Sternberg and Horvitz, 1984).

Plasma membrane of a muscle cell, covering the outisde of myofilament network, the muscle belly and the muscle arms.

Sarcomere

A single functional unit in the contractile portion of a muscle cell. Body muscle is obliquely striated with multiple sarcomeres in repeating fashion. Pharyngeal muscle is radial but not striated, with only a few sarcomeres per cell. There are many specialized muscles in male tail and in the vulva which are diagonal but not striated, and often consist of only a single sarcomere. There are several muscle sarcomeres that are organized circumferentially, in particular, the sphincter and one of the uterine muscles.

Striations consist of oriented members of the myofilament lattice, which are anchored to dense bodies on the plasma membrane. The orientation of the lattice elements (oblique to the body axis, or diagonal, or radial) determine the angle of the striations and of the whole muscle. Some smooth muscles in the nematode appear to be organized without recognizable sarcomeres, such as the gonadal sheath and the sphincter muscles.
           

See Dense body
See Myofilament lattice
See Smooth muscle
See Z band

Cytoplasm of any muscle cell, especially referring to that portion of the cell body near the nucleus.

See Muscle arm

A subset of the smooth endoplasmic reticulum which runs as thin membrane-bound tubules along the dense bodies of muscles. These tubules may sequester calcium ions for release during muscle contraction in response to nerve impulses. These structures are quite thin and appear discontinuous in thin section due to their tortuosity in C. elegans.

See Synaptonemal complex

This term can apply to similar structures at a variety of different levels, from tissues, to cells, to cell parts, to molecules.

Provided by sheath cell processes for axonal outgrowth (Antebi et al., 1997) and by GLRs for muscle arm outgrowth.

Alternately, the same term can refer to subcellular features. Some plasma membranes are reinforced by “scaffolds” either on the outside by 1) basement membrane on the basal surface, or by 2) glycocalyx on the apical surface, or 3) reinforced on the cytoplasmic side by surface coats made from cortical cytoskeleton, spectrin and cytoplasmic linkers, as well as a variety of uncharacterized molecules, many of which add visible electron density to the inner leaflet when viewed by TEM.

Cytoskeletal elements such as microtubules or intermediate filaments or PSD-containing subsynaptic proteins may be “decorated” by specific proteins over their length, thus acting as a scaffold onto which are positioned microtubule-associated proteins (MAPs), junctional proteins, synaptic receptors, etc.

See Basal lamina
See Glycocalyx
See Spectrin
See Undercoat

A cell whose cell body and/or extended processes provide the substrate which acts to shape the differentiation of another tissue. Several different cell types fit this general description:

1) The GLR cell bodies mark the position at which head muscles project their arms inward and the GLRs’ extended processes act as the substrate over which these muscle arms form a thin cylindrical plexus or motor plate onto which the nerve ring motor neurons form neuromuscular junctions.

2) The spike cells of the tail tip, and their epithelial covering by hyp10, also fit this definition. The spike cell syncytium acts as a scaffold for a posterior extension of hyp10, while the hyp10 extension acts as a scaffold for the secreted spike of cuticle at the extreme tail tip.

3) The XXX cells of the lateral lips and their extended anterior processes seem to provide a scaffold for the early elongation of the ventral bodywall muscles, and for the separate paths of the amphid nerve and the mechanosensory nerves. They may also organize the relative positions of the various socket cells of the lateral lips.

4) The anchor cell (AC) of the vulva acts as a scaffold for the formation of the uterine seam (utse) in order to connect the vulval passageway to the two lobes of the uterus.

A local hardening of the cuticle, usually accompanied by distinctively darker, more electron dense specialization, sometimes running uniformly across the layers, or sometimes showing parallel striations across the layers. Such specialization is most dramatic at the hook and spicules of the male tail, which are used as physical anchorages during male mating behavior. They are also found in many other portions of cuticle that are subject to high stress, such as along the buccal and pharyngeal passageways and the grinder, or at the excretory pore.

A commonly used detergent which can kill all stages except dauers and some eggs. It is often used to clean contaminated cultures or to produce staged cultures.

A subtype of adherens junction between neighboring sheath and socket cells whose apposing plasma membranes are exceptional tight, effectively sealing the internal pocket from contact with the pseudocoelom.

See Adherens junction

This term most often refers to the hypodermal seam cells, which lie along the lateral bodywall to form longitudinal stripes of epithelial cells underlying the alae, and are apparently responsible for formation of the alae themselves (Singh and Sulston, 1978). These differentiated cells also act as blast cells that can later give rise to specialized sensory structures such as the male tail rays. In late larval development, the seam cells mature and fuse to form a continuous syncytium along the bodywall, separate from the hyp 7 syncytium.

The term can also refer to the uterine seam (utse), another epithelium that acts to bind the vulval epithelium to the uterine epithelium, forming a three-way junction linking the single vulval passageway to the anterior and posterior lobes of the reproductive tract. This structure is created by the fusion of several precursor cells, and initially forms over the anchor cell, which acts as a scaffold.

See Foraging
See Leaving behavior
See Mate-finding

See Phasmidia

The most posterior portion of the pharynx which has an enlarged round shape. This is a major subdivision of the pharynx, lying between the isthmus and the pharyngeal valve. The bulb contains several large radial pharyngeal muscles, some neurons, and three large gland cells (Albertson and Thomson, 1976).

Cells and tissues that form from the C lineage, principally comprised of posterior hypodermis and some neurons.

See Primary ectoderm

A type of interneuron that lies downstream from primary interneurons, and which directs its own synaptic output to command interneurons, rather than motor neurons.

See Command interneuron
See Primary interneuron

The cells and tissues that form from the D lineage, consisting solely of some bodywall muscles.

See Primary mesoderm

The second most mature oocyte within the gonad, lying next to the primary oocyte.

See Primary oocyte

The daughter cells that result from the meiotic division of the primary spermatocyte, which maintain a syncytial relationship via a common residual body. Secondary spermatocytes mature by transferring some materials to the residual body, after which they detach to form spermatids.

See Primary spermatocyte

See Excretory cell
See Excretory duct cell
See Excretory gland cell
See Excretory pore cell
See Gland cell
See Seminal vesicle
See Vas deferens

Elaborate, highly specialized junctions where the excretory gland, excretory canal and excretory duct come together and join up to allow outflow of gland granules and canal urine into the duct. Perhaps a specialized form of adherens junction.

See Secretory membrane

Four cell types (1 pore cell, 1 duct cell, 1 canal cell and a fused pair of gland cells) make up the excretory system. The secretions of this system empty through the excretory duct and pore on the ventral side of the head. This system allows the animal to secrete saline fluid and maintain a proper salt balance. Other secretions, some postulated to play a role in molting, are also secreted.

SG

Secretory body (S)

A membrane-bound vesicle found in the cell cytoplasm containing stored material bound for export from the cell. The secreted material could be, among other possibilities, a hormone or signaling molecule, an enzyme or kinase, an energy store (yolk), or a glycoprotein destined for the glycocalyx or cuticle. Secretory granules are generally larger in dimensions than the secretory vesicles found in neurons. Granule contents may be delivered into the pseudocoelom, into the lumen of an epithelium, into a secretory duct or channel, into the external environment or the underside of the cuticle. Granule secretion is more often apical than basal.

Excretory junction (S)

A specialized portion of the plasma membrane of the excretory gland cell to the excretory duct through which the gland releases the contents of its secretory vesicles, through a region in which the apposed membranes are also heavily reinforced by adhesive specializations on their cytoplasmic surfaces.

See Secretory-excretory junction

A specialized organelle on plasma membrane of apical hypodermis, possibly involved in cuticle deposition. It is almost always closely associated with a mitochondrion.

See Secretory granule

C. elegans does not show clear regional segmentation across tissues; however, there is a repeating pattern to the organization of many body systems that is reminiscent of segmental organization. The clearest regional demarcations are in the head and tail, where many tissues show local specializations that are unlike the body region. Some authors have further recognized “developmental regions” along the length of the body that are somewhat like segmental organization (von Ehrenstein and Schierenberg, 1980).

A category of adherens junction in which a cell forms a junction onto itself, usually in order to form a complete ring around another structure. This is a common feature in socket cells where they form a complete seal at the opening of a sensillum.

See Adherens junction

Progeny that derive from self-fertilization of a spermatozoon and an oocyte from within the hermaphrodite gonad, not involving a mating event with a male animal.

The act of internal fertilization of sperm and oocyte deriving from a single parent animal to produce self-progeny. Thus a single C. elegans hermaphrodite, living apart from any fertile partners, can produce over 200 self-progeny who derive all genetic material from the one parent.

Spermatozoa derived from the hermaphrodite germline and not from the male. These are typically smaller and less motile than sperm from a male.

See Sperm competition

Self-fertilization (S)

Most C. elegans are hermaphrodites and have this capability to produce “self-progeny” by internal fertilization, combining male and female gametes produced by the germline of the parent animal. This process is different from parthenogenesis, in which a new animal is produced from the fission of a single gamete by asexual means.

See Cross-progeny
See Inbred / Inbreeding
See Outcross

Fluid ejaculated by the male’s seminal vesicle along with the spermatozoa. It may contain soluble factors which activate sperm motility or sperm’s competence to fuse with the oocyte (L’Hernault, 1997; but see LaMunyon and Ward, 1995).

Structure (in the male gonad only) which houses the maturing sperm cells prior to mating. It is a tube-like structure formed from 20 secretory cells that are surrounded by a sheet of cytoplasmic processes formed from 3 large cells. These somatic cells derived principally from Z1.pp or Z4.ap (Kimble and Hirsh, 1979).

Chemicals that mediate interactions between organisms. They are subdivided into allelochemicals (signaling to members of other species) and pheromones (signaling within the same species).

See Allelochemical
See Pheromone

An aberrant condition in which one “half vulva” (anterior or posterior) develops independently from the other due to loss of precursor cells for the other half (due to laser ablation or mutation).

See Pseudovulva
See Vulva

A sensory organ, generally made up of one or more sensory neurons whose dendritic endings are protected by one or two accessory cells, and a thin wrapping of hypodermis.

See Amphid
See Amphid image gallery
See Cephalic sensilla
See Cephalic Image gallery
See Deirid
See Deirid image gallery
See Labial
See Inner & Outer labial image gallery
See Phasmid
See Phasmid image gallery
See Hook sensillum
See Postcloacal sensillum
See Ray
See Spicule

A non-associative learning response where there is an increase in the magnitude of response following repeated administrations of a stimulus.

See Learning and memory

Neuron having a mixed modality of cell functions, including both sensory transduction (by its dendrite) and motor output (via its neuromuscular junctions).

See Mixed modality

The animal’s responsiveness to the prolonged or repeated exposure to a sensory stimulus (chemical taste, olfaction, osmotic barrier, temperature, touch) which usually shows a decrease. In most cases, upon removal of the stimulus, the sensory response will later recover (Jorgensen and Rankin, 1997). Olfactory adaptation is more complex, and some odorant responses do not adapt (Bargmann and Mori, 1997). These short term adaptations could be governed by changes in receptor responsiveness in the dendrite, or by changes in synaptic efficacy between sense cells and interneurons or motorneurons.

See Adaptation
See Habituation

The only ciliated cell type in C. elegans is the sensory neuron. Of the 302 neurons in the adult hermaphrodite, 60 of them are ciliated. Males have an additional 52 ciliated neurons, most of which are found in the tail (for detail see Inglis et al., 2007).

See Sensillum
See Sensory neuron

Neuron that is involved in responding to external stimuli such as chemosensation (Bargmann, 2006), thermosensation, osmosensation or mechanosensation (Goodman, 2005).

Most sensory neurons are ciliated in structure (Inglis et al., 2007), except the touch neurons (ALM etc), the PVD neurons and perhaps a few others.

See Sensillum
See Sensory cilia

Ray (S)

A long thin bristle-like specialization embedded in the fan cuticle of the male tail, consisting of extended processes of three cells (RnA, RnB, Rnst), two ray neurons and a support (structural) cell , all wrapped within a thin layer of hypodermis. At the distal end the structural cell expands to form a pocket enclosing the ciliated endings of the two sensory neurons. At the tip there is a narrow pore which opens this pocket to the exterior to expose the cilia to the outside environment.

See Ray

Each sense receptor organ, or sensillum, contains one or more ciliated nerve endings and two non-neuronal cells, a sheath and socket cell. Most receptors are located in the head, which is where most sensory functions take place. Some sensory “receptors” exist as diffusely localized membrane channels in one or more neuronal processes that do not involve a cilium (such as PVD’s highly branched arbor along the bodywall, or the diffuse sensory channels in an ALM dendrite).

See Sensillum

Most ciliated nerve endings are either exposed to the environment via openings in the cuticle or they terminate or embed within the cuticle. Two unusual sensory neurons, AQR and PQR are exposed to the pseudocoelomic cavity of the worm. For detailed list see Table in Inglis et al., 2007.

See Sensillum
See Sensory receptor

Usually refers to an intercellular junction found in the spermatheca and perhaps in the vulval epithelium. Here the two plasma membranes are separated by a distance to each other (the septum), and electron dense specializations mark the cytoplasmic borders in a “pleated” (ladder-like) pattern. The term can refer to both the pleated septate junction and to the continuous (smooth) septate junction, which displays a wide intermembrane spacing (is septated) but shows no visible pleating.

See Continuous junction

The division of a cavity into parts by a septum. Used to refer to a mutant phenotype of excretory canal cells where neighboring cystic portions of the lumen become partially septated (Buechner et al., 1999). Inside the uterus, the egg chamber may also have temporary septations separating one embryo from the next.

See Smooth endoplasmic reticulum

set

Seam cell syncytium (S)

SET refers to the five most posterior seam cells in the male, which fuse to form a syncytial compartment in the male tail, after the generation of the ray cell groups. Unlike the most anterior seam cells in the male which make alae, the SET cells do not make this cuticular structure.

See Tail seam
See Ala / Alae

Stiff bristle-like sensory features that occur in some nematode species, as opposed to shorter nipple-like sensory structures, known as papillae. In C. elegans, very few sensilla form true bristles (except for the spicules and perhaps the rays), but some shorter papillae are common (including the inner labials, cephalics, post-cloacal sensilla, and the hook sensillum).

See Papilla/ Papillae

Sex determination

C. elegans has two sexes. Hermaphrodites are diploid with five pairs of autosomes and two X chromosomes. Males have the same number of autosomes, but only have one X chromosome. Gametes produced by hermaphrodites are all haplo X so they give rise to nearly all XX hermaphrodite self progeny except for the rare male formed from X-chromosome loss. Males produce haplo-X and nullo-X sperm so cross progeny with a hermaphrodite will produce half male progeny.

Most differences between the sexes develop postembryonically by different cell-specific patterns of gene expression. In somatic cells, the sex-specific fate of different cells is controlled by the master regulator tra-1 which acts as a transcriptional repressor in hermaphrodites. In the germ line, regulatory interactions of additional genes are required to specify sexual fate.

For more information see chapters in Wormbook (Herman, 2005; Ellis and Schedl, 2007; Zarkower, 2006).

The muscles of the adult reproductive system. In hermaphrodites, these include the vulval and uterine muscles, located near the vulva in the midbody, which all derive from the M myoblast.

In adult males, the M myoblast gives rise to a much larger set of specialized muscles for male mating which differentiate within the tail region (See Wormatlas Muscles of the Male Part 1 and Part 2).

SM

Sex mesoblast (S) M cell (S)

In the hermaphrodite, the postembryonic blast cell, M, begins dividing during the L1 larval stage to produce bodywall muscles plus two daughter myoblasts. These two daughter myoblasts migrate within the body and divide during the L3 and L4 larval stages to produce the sex muscles of the vulva and uterus.

In the male, the same sex myoblast again gives rise to many bodywall muscles plus six myoblasts in the L1 stage. These six myoblasts migrate posteriorly and divide during L3 and L4 stages to produce the specialized mating muscles of the adult male tail.

See Pheromone

Property by which different sexual forms of a species assume different body size and/or shape. C. elegans is moderately dimorphic in size, since males are slimmer than the hermaphrodites. They also have distinct anatomical differences. Externally, the adult hermaphrodite has visible vulva, while the adult male tail becomes reorganized in order to form a distinctive mating structure. The internal reproductive organs also differ between male and hermaphrodite and there are substantial changes in musculature and nervous system. Some other nematode species are much more dimorphic in size and shape.

The term can also be used to refer to alterations in the cell fate for a specific cell between the two sexes (such as the M myoblast ). A specific cell may live and differentiate in one sex, but undergo cell death, serve as a blast cell or merely change shape in the other sex. These differences in cell fate (large or small) are also considered individual sexual dimorphisms.

This term has several distinct meanings.

An enclosed channel formed by the sheath and socket cells to house the distal components of sensory dendrites of a sensillum, or of an external structure such as the spicule.

A layer of epithelial cells that enclose another tissue, such as the gonadal (ovarian) sheath which encloses the germ line.

More commonly known as the embryonic sheath, a lipid layer covers the embryo before elongation and is thought to serve as a template for cuticle annulations. The first cuticle is made at L1 and replaces the sheath (Priess and Hirsh, 1986).

Additionally, the term has been used in nematode literature to refer to a shed cuticle [post-molting] that has been retained over a portion of the body, especially in the case of dauer formation (Yarwood and Hansen, 1969).

See Embryonic sheath
See Sheath cell
See Sheathed

An interfacial epithelial cell which forms a specialized environment surrounding the ciliated sensory ending(s) of one or more neurons and is often accompanied by a more distal socket cell (example). Some sheath cells also extend thin wrapping processes around bundles of axons in the nerve ring. In early development of the sensory nerves and of the nerve ring, some sheath cells (cephalics and labials) may also provide a substrate for axon guidance.

Another category of sheath cells (SPsh) encloses the spicule channel in the male tail and apparently secretes cuticle which lines the channel.

See Glia table
See Gonad sheath
See Ovarian sheath
See Socket cell
See Spicule
See Structural cell

The external space or cavity created by the sensory accessory cells (sheath and socket cells, or structural cell) that enclose the sensory cilia of most specialized sensory receptors. In chemosensory sensilla (such as in amphids), this space is open to the exterior environment via a pore created by the socket or structural cell, but in other cases the space is usually sealed closed beneath the cuticle (as in outer labial and cephalic sensilla).

See Amphid channel

A prominent feature in the amphid sheath cells, lying in the sheath process near the amphid pocket. This large flattened multilamellar structure is likely to be an enlarged Golgi apparatus, and appears to shuttle material to the pocket in small vesicles (Perkins et al., 1986). Smaller sheath lamellae are found in the sheath cells of other sensilla, including the cephalics and the phasmids.

A term used to refer to those amphid cilia that end within the sheath or in cryptic locales (those of AFD, AWA, AWB and AWC), as opposed to those cilia that are directly exposed to the environment through the amphid pore (the amphid chemoreceptors).

The property of being confined within an extra cuticle layer. In some nematodes, early larval cuticle layers may be retained as outer sheaths, providing an added layer of protection from the external environment. Sheathed animals often cannot feed due to interference of the excess cuticle. “Exsheathment” defines the process by which the animal finally loses this layer or layers. Although wild type C. elegans is rarely, if ever, sheathed, some molting mutants can cause full or partial cuticle retention.

See Exsheathment

A typical nematode behavior in which the body becomes locally foreshortened without any bending motion. This is typically seen as a head withdrawal from an aversive stimulus to the nose, or as a shortening of the posterior body as part of the defecation motor program, but is seen in exaggerated form in the mutant shrinker phenotype.

See Shrinker phenotype

A rather rare mutant behavior in which the whole body undergoes longitudinal shortening in response to head touch or tail touch. These animals are generally unable to generate normal body waves, and apparently lack reciprocal inhibition of the dorsal and ventral body muscles.

Cuticle projections (finger-like) into the pharyngeal lumen that form a meshwork which may act to filter or retain contents of the lumen. They lie within the metacorpus (1st bulb).

See Buccal filter

A category of specialized muscle cells in which all muscle filaments are organized into a single well ordered motor unit, with all thin filaments lying in close register to a single band of dense bodies on each end of the cell.  In C. elegans, this category includes many of the muscles of the male tail and the radial muscles of the pharynx.

See Radial muscle
See Smooth muscle
See Striated muscle

An extracellular cavity or tube formed by an epithelium or within a single cell. While the term is usually used with regard to tissues involved in excretory or secretory functions, it can also refer to the lumena of the pharynx or digestive tract.

The pattern of body motion produced as the whole animal crawls forward. The muscles on one side contract while the muscles directly opposite relax in synchrony such that a smooth wave of contraction passes along one side of the body to cause a smooth deep bend in the body.

See Locomotion

See Paternity

Archaic name for the cell extension of the GLR cells whose projections run just under the nerve ring. These 6-fold cells each run about 60^o around the ring and thus encircle the whole isthmus (6 x 60 degrees = 360) (Ware et al., 1975).

Hypodermal system (S)

This term is rarely used in C. elegans literature (See Podbilewicz, 2006).

See Turning

A mode of toxic interaction in which a bacterium invading the host nematode does not quickly poison or kill the host, but chooses to colonize the animal and reproduce itself for an extended period prior to toxin production (Darby, 2006).

sma
micro
dwarf
pygmy

Produces a “miniature” adult worm, as opposed to a “dumpy” phenotype, in which a more normal sized adult worm seems to be squished into a very tight, constricting cuticle that is foreshortened and rather bulging (Zimmerman and Padgett, 2000).

Earlier workers had found similar spontaneous mutants in C. briggsae (the “micro” mutant of Nigon and Dougherty, 1950) and in C. elegans (the “dwarf” race of Dion and Brun, 1971), and after mutagenesis in C. elegans (the “pygmy” race of Nigon and Dougherty, 1954 which may have been lost).

SER
Smooth ER

A subdivision of the endoplasmic reticulum (ER) that is prominent in certain cell types in C. elegans, including muscle, neurons, and intestine, but is reduced or absent in others (Rolls et al., 2002).

See Rough endoplasmic reticulum

A muscle cell in which the endpoints of thin and thick filaments are not highly ordered, and do not show periodic striations as in striated muscles. In smooth muscles, some thin filaments are perhaps not well anchored to dense bodies or hemidesmosomes on the plasma membrane, but float freely among the thick filaments to produce thinner wispy muscle elements rather than well defined sarcomeres. Smooth muscles are common in certain locales within the nematode where they act to squeeze diffusely over valves or strictures in the digestive system and reproductive system.

See Striated muscle

See Continuous junction

The anterior end of the head, including the lips and buccal opening and the related anterior sensilla.

Aggregation behavior (S)
Solitary feeding (A)

A distinctive behavior in which individual nematodes choose to move together into large groups to feed together, rather than separately. In C. elegans, the behavior seems to be under the influence of an external pheromone that is received by several amphid neurons (De Bono et al., 2002) and of a second internal chemical signal, acting via the pseudocoelom and received by a separate set of sensory neurons (Coates and De Bono, 2002). When animals choose to feed separately from their neighbors, this is called “solitary feeding”. Some wild strains of C. elegans show social feeding, including the Hawaiian strain CB4856.

See Bordering
See Pheromone

An interfacial epithelial cell which forms a distal cap on a sheath cell to bind the sheath of a sensillum to the neighboring hypodermis, via adherens junctions. There is often a narrow opening through the socket from the exterior into the sheath channel, allowing ciliated dendrites to be exposed to the external environment. The socket cell functions similarly to a glial cell.

In some cases the socket cell function is provided by a hypodermal blast cell, but the function segregates to a socket cell during later larval and adult stages after birth of the socket cell proper. In some sensilla (such as the phasmid) which have multiple socket cells, one socket forms the sensillar opening, while the extra socket cell(s) form wrapping processes along the side of the sheath cell ending. For some sensilla the sheath cell can also serve socket cell functions (for instance the structural cell of the sensory rays of the male tail).

See Glial cell
See Glia table
See Sheath cell
See Structural cell

See Social feeding

Cell body (S)
Perikaryon (S)

Greek derived word meaning "body" it refers to the bulbous portion of a neuron that contains the cell nucleus as well as other cellular organelles.

See AB blastomere

The components of the gonad that are separate from the germline proper. These include five tissues which are all derived from the somatic primordium : the distal tip cells, the gonadal sheath, the spermatheca, the spermatheca-uterine valve (sp-ut) and the uterus.

See Somatic primordium
See Distal tip cell
See Gonad sheath
See Spermatheca
See Spermatheca-uterine valve
See Uterus

The pattern of cell divisions stemming from the one cell fertilized embryo is highly stereotyped in C. elegans. The cell divisions which produce the cells other than the gametes (germ cells) are called the “somatic lineage” are highly reproducible. The latter cells derive from the “germline lineage”, which does not follow a reproducible pattern.

The set of precursor cells that later give rise to the somatic tissues of the gonadal tract. This lineage is comprised of ten cells descended from Z1 and Z4 that reorganize spatially in the L2 larva during a lull in mitotic divisions of the somatic gonad (Kimble and Hirsch, 1979). Final lineage patterns, among four of these ten cells, depend upon a signaling event within the primordium in which one of two cells adopts an anchor cell fate, while the other becomes a stem cell (Pepper et al, 2003). The two alternate lineage patterns are termed “5L” and “5R”, where Z4.aaa or Z1.ppp, respectively, adopt the anchor cell fate, yielding a total of five somatic cells on one side and four cells on the opposite side.

Any tissue forming the body of an organism. This excludes the germline.

The initial recipient of material that is internalized by clathrin-dependent and independent endocytosis.

See Endosome
See Recycling endosome

See Membranous organelle

A specialized extension of the Golgi complex on the cis face, seen in the germline (Wolf et al., 1978), where an extension of ER membrane passes through a tight cytoplasmic “collar” to form smaller vesicles on the cis face. The special vesicle may act to shuttle material to the fibrous body, where a very similar fibrous collar organizes the connection of the vesicle to the outer leaflet of the plasma membrane surrounding the fibrous body and form “finger-like projections” (Wolf et al., 1978). Still later, the special vesicle is possibly involved in the dissolution of the fibrous body and the creation of the membranous organelle in the late spermatid.

See Collar
See Finger-like projections
See Membranous organelle

An important cytoskeletal protein which forms a meshwork on the cytoplasmic surface of the plasma membrane, likely functioning to provide structure and reduce flexibility of the lipid bilayer. Spectrin networks give strength to the plasma membrane in all cells, and are essential for the integrity of neuronal processes during body motion (Hammarlund et al., 2007). Spectrin is a tetramer and is composed of two α and two β chains; each β chain has an actin binding domain at its amino terminus. The spectrin meshwork is linked to actin filaments within the cell cortex and they jointly act to control the formation of filopodia, lamellipodia, and the extension of cell processes. These are especially significant in migrating cells and neuronal growth cones. Spectrin is encoded by the sma-1 gene in C. elegans.

The mature male gamete, which merges with an oocyte to create a fertilized embryo inside the uterus. Sperm are produced from primordial germ cells during embryonic development of the hermaphrodite gonad and stored in the spermatheca. They are also produced in the mature gonad of the male animal and there are stored in the vas deferens and seminal vesicle prior to ejaculation during mating.

See Spermatozoon

A specialized form of nuclear aster that participates in forming the meiotic spindle in the early one-cell embryo (Srayko et al., 2000). The sperm aster also interacts with the actin cortex of the one-cell embryo to establish the orientation of the A/P axis (Lyczak et al., 2002).

The action of the sperm from multiple sexual partners competing to fertilize the oocyte. Since in C. elegans the hermaphrodite also produces her own sperm internallyl, sperm competition also refers to the relative success of internally derived sperm compared to sperm derived from male matings. Male-derived sperm are larger and more motile than hermaphrodite-derived sperm and thus are more successful, predominating over sperm derived from the hermaphrodite such that nearly all the oocytes are fertilized by the male-derived sperm (Ward and Carrel, 1979; LaMunyon and Ward, 1995, 1998, 1999; Singson et al., 1999).

See Sperm precedence

A category of mutations in which the animal (hermaphrodite or male) produces defective sperm and/or no sperm, and therefore becomes infertile or displays reduced fertility. The fertility of a “sperm defective” hermaphrodite can often be rescued by mating with a normal male.

A feature observed in post-copulatory hermaphrodites in which contractions of the uterine sheath cause sperm to leak out from the vulva. This behavior is thought to be associated with mating resistance by the hermaphrodite (Kleeman, 2005).

The ability of spermatozoa to move actively when released from the vas deferens (of the male) or from the spermatheca (of the hermaphrodite). Unlike most sperm which move via the action of a flagellum, nematode sperm crawl with a pseudopod where membrane cycles from the tip to the base resulting in a "treadmilling" of the plasma membrane. Motility has been shown to vary with the absolute size of the spermatozoon with larger sperm having an increased fitness in mating competitions within the hermaphrodite gonadal tract (LaMunyon and Ward, 1994, 1995, 1998, 1999).

See Pseudopod
See Sperm competition

The tendency of sperm from one particular parent to predominate in their success in fertilizing the oocytes of a hermaphrodite (or female). Male sperm tend to show strong precedence over sperm derived from the hermaphrodite, thought to be due in part to the larger size of male sperm (LaMunyon and Ward, 1999). When a hermaphrodite is mated with several males, sperm precedence can refer to the success rate of sperm from one male to predominate over sperm from others. First-male precedence indicates that the sperm from the first male to mate with the hermaphrodite lead to the most progeny while second-male precedence refers to cases where sperm from the second male lead to more progeny (LaMunyon and Ward, 1998).

See Sperm competition
See Copulatory plug

A step in the process of male mating, during which the male ejaculates mature sperm from his vas deferens into the vulva and then into the uterus of the hermaphrodite reproductive tract. This process has several steps including the initiation of sperm transfer, the release and continued transfer of sperm and the cessation of sperm transfer (Schindelman et al., 2006). After transfer to the hermaphrodite, the sperm migrate through the uterus to the spermatheca.

A somatic gonad structure (found only in the hermaphrodite) that connects the distal gonad arm to the uterus. It is composed of 24 cells that form a tube-like structure and acts as a reservoir for maturing spermatids and adult sperm which wait for an opportunity to fertilize a passing oocyte.

See Spermathecal lumen

The central passage bounded by the 24 epithelial cells of the spermatheca, through which germ cells pass between the gonad arm and the uterus. The width of the lumen is usually very narrow, but as the basal surface has many longitudinal folds, it can undergo radial expansion to accommodate passage of a primary oocyte. Circumferential dilation of the distal spermatheca during ovulation is triggered by activation of the TRK pathway by the maturing primary oocyte (Clandinin et al., 1998; McCarter et al., 1999; Bui and Sternberg, 2002).

See Spermatheca

Spermathecal uterine junction (S)
sp-ut valve (S)
sujn (S)

A set of four cells (sujn) which act to restrict mature gametes from passing from the spermatheca to the uterus or vice versa. Prior to adulthood, the valve is completely blocked by the presence of two core cells (sujc) in the valve lumen. These are expelled at the beginning of egg-laying to permit the passage of oocytes through the spermatheca and into the uterus. Opening of the valve also permits the passage of sperm acquired from mating with males into the spermatheca, where they will compete with hermaphrodite-derived sperm to fertilize these oocytes.

See sujc cell
See sujn cell

The secondary spermatocytes undergo a second meiotic division to form four haploid spermatids. Initially they are connected via a central structure called the residual body, but once they have rid themselves of unneeded biosynthetic materials, they detach and are then stored within the spermatheca (in the hermaphrodite) or in the seminal vesicle (in the male). Eventually a spermatid matures, via spermiogenesis, into a spermatozoon, either within the gonadal tract or after ejaculation.

See Residual body
See Spermatocyte
See Spermatozoon

There are two different forms of this cell, the primary spermatocyte (diploid) and the secondary spermatocyte (haploid). The primary spermatocyte forms in the male gonad when a spermatogonial stem cell buds off from the rachis to form a single cell that quickly enters metaphase I and divides to form secondary spermatocytes attached to a residual body. Secondary spermatocytes undergo a second meiotic division to complete meiosis, at which time the daughter cells detach from the residual body to become spermatids. The L4 hermaphrodite gonad contains essentially similar primary and secondary spermatocytes prior to switching to produce oocytes during adult life.

See Primary spermatocyte
See Secondary spermatocyte
See Spermatid
See Spermatogenesis

The process by which immature germ cells develop within the gonad from spermatogonial stem cells into spermatocytes, spermatids, and then mature spermatozoa (for more detail see L'Hernault, 2006).

See Spermiogenesis

A class of genetic mutants in which the affected adults produce defective sperm, and are therefore infertile (for more detail see L'Hernault, 2006).

Mitotically active diploid germ cells which are connected together via a central canal known as the rachis. They proliferate in the neighborhood of the distal tip cell of the proximal gonad, beginning in the early L4 stage and continuing to divide until late L4 stage (in the hermaphrodite) or throughout the fertile lifespan (in the male gonad). When these cells detach from the rachis they each become a primary spermatocyte.

See Rachis

The distal region of the male gonad where the mitotic germline cells lie beneath a basal lamina, some in direct contact with two distal tip cells. This can be considered the distal testis, while the proximal testis is called the seminal vesicle.

The fully mature male germ cell. It is haploid and fertilizes a haploid oocyte in order to produce a diploid embryo. In the nematode, the spermatozoon has no flagellum, but moves by amoeboid motion led by a pseudopod. It contains a condensed nucleus, tightly packed mitochondria and several distinctive membranous organelles.
           

See Pseudopod

The final steps of sperm maturation where it forms its pseudopod, acquires the ability to crawl and becomes competent to fertilize an oocyte. In hermaphrodites, this stage begins when the spermatids arrive in the spermatheca. In males, mating triggers spermiogenesis. This is a quick process (about 5 minutes) and does not require any new gene expression or protein synthesis.

See Spermatid
See Spermatozoon

Archaic term for dense-staining inclusions in the intestine that are non-birefringent.

See Gut granule
See Rhabditin

See Sphincter muscle

Several smooth muscle cells may act as sphincters for different organs, including the anal sphincter cell (mu sph), the spermathecal uterine valve (sujn), and possibly the control of the vas deferens and the m8 muscle of the pharynx.

See Anal sphincter muscle
See m8 muscle cell
See sujn

See Rectal valve

Archaic term

See Gubernaculum

Two elongated sclerotized structures in the male tail which are actively everted during copulation to fasten the male copulatory fan to the hermaphrodite vulva. They consist of a long narrow tissue extension covered by a hardened layer of cuticle and are housed within bilateral spicule channels. The spicules are controlled by specialized muscles and contain specialized sensilla. Internal spicule tissue includes process extensions from neurons, socket and sheath cells and a thin hypodermal covering, similar to the rays. In some species of nematode (not C. elegans), the spicules open at the tip via a pore to allow the internal sensory cilia to be exposed to the exterior (Clark and Shepherd, 1977).

A long narrow cuticle lined canal which indents into the gubernaculum in the male tail. The canal is formed by the spicule sheath cells and opens to the exterior. The two spicules are housed within these two parallel canals when at rest, but can be extended out of the canals by action of the spicule protractor and gubernaculum evertor muscles.

See Amphid channel
See Gubernaculum

A step in mating behavior in which the male inserts his spicules into the vulva of the hermaphrodite in order to secure a firm grip on her prior to sperm ejaculation. Spicules are pushed outward from the spicule channels by the action of the spicule protractor muscles of the male tail.

The spicules are associated with three sets of muscles.

See Anal depressor muscle
See Protractor muscle
See Retractor muscle

A late step in male mating in which the male retracts his spicules, releasing his grasp on the vulva of the hermaphrodite. Spicules are pulled back into the spicule channels by action of the spicule retractor muscles.

See Male mating behavior
See Spicule
See Spicule channel

Two short-lived hypodermal cells in the early embryo which fuse to form a syncytium by the tadpole stage.Thse cells undergo programmed cell death during late embryogenesis at which time they leave behind a narrow spike of cuticle, often called the tail spike (Sulston et al., 1983).

See Tail spike

Most often refers to the mitotic or meiotic spindle formed by microtubules for properly alignment and separation of the chromosomes during nuclear division.

Alternately, the same term has been used in older nematode literature to refer to the contractile filament lattice of the muscle sarcomere (Bird and Bird, 1971, 1991).

The balance of forces, derived from opposing forces produced by many microtubule-based motors operating along the astral microtubules, which collectively pull upon and give shape to the mitotic spindle.

Proper orientation of the spindle is critical during the early divisions of the embryo (one cell, two to six cell) as rotation of the spindle aids results in asymmetric cell division and establishes the principal axes of the nematode body plan (Gönczy and Rose, 2006).

A term sometimes used to refer to a local synaptic branch of a neuron. Such structures can be very prominent in larger nematodes such as Ascaris (Rosenbluth, 1965). In C. elegans the term is rarely used, as most synapses occur en passant, and synaptic branches tend to be small and rather inconspicuous.

A large, multi-component ribonucleoprotein complex which performs the two transesterification reaction steps of pre-mRNA splicing (see Zahler, 2005 for more details).

Male progeny are generated by two mechanisms in the nematode:

1) During sexual reproduction according to the distribution of X chromosomes among progeny. When an XX hermaphrodite mates with an XO male, half of the progeny will receive a nullo-X sperm producing an XO karyotype and become males.

2) The self-progeny of hermaphrodites can also become male by the “spontaneous” loss of one X chromosome during meiosis in the germline. These males are identical to males produced from sexual reproduction in development and behavior and can only reproduce by sexual interaction with another hermaphrodite. Spontaneous males occur at a rate of 1/700 to 1/2000 in wild type C. elegans (Bergerac vs Bristol strains) but are more frequent in him mutant strains in which segregation of the X chromosome is disturbed (Nigon, 1949; Hodgkin et al., 1979; Hodgkin, 1980).

See Male stock