Fig. 6. Overlapping expression of ehn-3, tra-1 and hnd-1 in embryonic SGPs. hnd-1, tra-1 and ehn-3 are expressed in the SGPs at different, but overlapping, times during embryogenesis. hnd-1::GFP is first detected in SGPs migrating towards germ cells and disappears about the two-fold stage of embryogenesis. TRA-1 is detected in newly formed gonadal primordium and may be expressed earlier in migrating SGPs (M.S. and A.S., unpublished). TRA-1 continues expression in SGPs during embryogenesis and into the first larval stage, when its level and distribution are modulated in the two sexes. EHN-3::GFP is expressed exclusively in SGPs shortly after gonadal primordium forms; it disappears by the threefold stage of embryogenesis.