FOG-1 protein was not detected in 89% of
fog-2 XX gonads at any time of development; the remaining 11% showed weak staining that never acquired the intensity typical of prespermatogenic nuclei and was only found later than normal, in mid or late L4 larvae. Therefore, FOG-2 controls the onset of hermaphrodite spermatogenesis, at least in part, by promoting FOG-1 expression in young larvae.