Organogenesis in C. elegans: positioning of neurons and muscles in the egg-laying system.

One of the final stages in the development of egg-laying behavior in the nematode C. elegans is the organization of 8 motor neurons (2 HSN and 6 VC cells) and 8 muscles into a motor system to control the opening of the vulva. Using mutations that disrupt the development of specific components of the egg-laying system and laser microsurgery to ablate selected precursor cells, we have determined that the guidance of the egg-laying neurons and muscles, and in particular the VC neurons and vulval muscles, into the vulval region is dependent on interactions with surrounding epithelial and gonadal tissue and appears to be independent of neuron-neuron and neuron-muscle interactions. The development of the egg-laying system can be described as a series of cell interactions in which certain cells arise through induction and subsequently provide inductive cues themselves.