During the development of the nematode, Caenorhabditis elegans, cell fates are determined via a combination of cell-autonomous and cell-nonautonomous mechanisms. The latter, regulative phenomena, require the existence of one or more intercellular signaling pathways. In this review, we consider the function of two genes,
lin-12 (lineage abnormal) and
glp-1 (germ line proliferation defective), that are required for intercellular signaling during nematode development.