What other influences control germ cell fate?
The ablation of a single sheath/spermathecal precursor cell in the somatic gonad can completely feminize the germ line in XX animals (McCarter et al., 1997). This result suggests that a second somatic signal might influence germ cell fates, since her-1 is not expressed in XX animals. However, no ligand or receptor has been identified, and it is possible that these ablations exert their influence indirectly, by reducing the size of the germ line. Indeed, direct ablation of a subset of germ cells at the L2/L3 molt also completely feminizes some XX animals (McCarter et al., 1997). There is also a potential signal transduction pathway that promotes spermatogenesis, but whose mechanism of operation remains unknown. Genes of the ERK MAP Kinase pathway are required for several different germ cell fates, including the progression of cells through the pachytene stage of meiosis I (Church et al., 1995; Hsu et al., 2002). Partial loss of function of lin-45 Raf, mek-2 MEK and mpk-1 ERK can causes
