P450SCC-LIKE IMMUNOREACTIVITY THROUGHOUT GONADAL RESTRUCTURING IN THEPROTOGYNOUS HERMAPHRODITE THALASSOMA DUPERREY

The source of steroid hormones, which potentially regulate gonadal res tructuring throughout protogynous sex change in teleosts, remains larg ely unknown. To address this issue, immunocytochemical methods were em ployed to detect gonadal sites of steroidogenesis in the protogynous h ermaphrodite wrasse Thalassoma duperrey at different stages in the sex change process. Steroidogenic cells were classified based on the pres ence of P450 cholesterol-side-chain-cleavage-like immunoreactivity (P4 50scc-ir). P450scc-ir cells were predominantly in the thecal layer of normal females. As females underwent sex change, P450scc-ir localizati on shifted from the thecal layer to the interstitium. P450scc-ir cells appeared to increase in number midway through sex change. In sex-chan ged males, P450scc-ir cells were found in small clusters interspersed among spermatogenic lobules. These results demonstrate for the first t ime the ability of the gonad to produce potential steroidal mediators of gonadal restructuring throughout the sex change process.