|Anterior region of Cruznema tripartitum.|
|Rhabditid lip region, stoma and esophagus|
|Dauer larva; enduring survival stage; metabolically inactive; mouth closed; double cuticle.|
|Monovarial specimen showing spermatheca with sperm and distal end of reflexed ovary.|
|Spindle-shaped longitudinal muscle cells below the cuticle
and epidermis of a rhabditid nematode. The musculature is in four
strips, separated by the epidermal (hypodermal) chords. A process
extends from each cell to the dorsal or ventral nerve chord.
In Caenorhabditis elegans there are 24 mononucleate nerve cells in each subdorsal quadrant of the body, 24 in the right subventral quadrants and 23 in the left subventral quadrant. (Sulston and Horvitz, 1977; Waterston, 1988).
|Specimens from litter-soil interface, UC Davis campus. Photographs by H. Ferris.|
Under some conditions eggs are retained in the body of older females. The female dies, the eggs hatch, and juveniles feed on bacteria that are decomposing the maternal cadaver. The phenomenon has been termed "bagging" and "endotokia matricida". It has been variously interpreted as the result of diminished strength of the vaginal muscles that would be involved in allowing passage of the egg, and the resulting death of the worm (hence matricida), and also as a facultative vivipary, survival adaptation that provides resources for the juveniles (Chen and Caswell-Chen, 2004).
|Bagging or Endotokia Matricida: Juveniles
beginning to emerge from the depleted maternal cadaver of a rhabditid
Photograph by Jonathan Nivens
Chen, J, Caswell-Chen, E.P. 2004. Facultative vivipary is a life-history trait in Caenorhabditis elegans. J. Nematology 36:107-113.
Sulston, J.E. and H.R. Horvitz. 1977. Post-embryonic cell lineages of the nematode Caenorhabditis elegans. Developmental Biology 56:78:577-597.
Waterston, R.H. 1988. Muscle. Pp 281-335 in W.B. Wood (ed). The Nematode Caenorhabditis elegans. Cold Spring Harbor Laboratory.
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