Genetic regulation of germline sex determination.

The pathway consists of a cascade of regulatory interactions driving sexual fate. Essentially, fem-1, -2 and -3 together with fog-1 and fog-3 promote spermatogenesis. To allow hermaphrodite animals to switch to oocyte production at the late L4 stage, tra-2 is repressed by the action of FOG-2 and GLD-1. fem-3 is repressed at the level of mRNA by multiple factors. Thus, regulation of the balance of TRA-2 and FEM-3 levels allows the timely transition from sperm to oocyte production, in order to generate fully fertile hermaphrodites. Factors that promote male and female fates are highlighted in blue and red, respectively. Adapted from Kimble and Crittenden [14] and Rybarska et al.[41].