Figure 8 .

Vulval development in C. briggsae and the proposed roles of genes described in this study. P-cell migration into the ventral hypodermal region is mediated by the class 2 genes. Subsequently, P cells divide, and six of their posterior daughters (Pn.p, n = 3−8), termed VPCs, become capable of giving rise to the vulval tissue. Their competence appears to be regulated by the class 3 genes. VPC progeny differentiate and undergo morphogenetic changes during the L3 and L4 stages. The class 4 genes are required in these processes.