P450scc-like immunoreactivity throughout gonadal restructuring in the protogynous hermaphrodite Thalassoma duperrey

The source of steroid hormones, which potentially regulate gonadal restructuring throughout protogynous sex change in teleosts, remains largely unknown. To address this issue, immunocytochemical methods were employed to detect gonadal sites of steroidogenesis in the protogynous hermaphrodite wrasse Thalassoma duperrey at different stages in the sex change process. Steroidogenic cells were classified based on the presence of P450 cholesterol-side-chain-cleavage-like immunoreactivity (P450scc-ir). P450scc-ir cells were predominantly in the thecal layer of normal females. As females underwent sex change, P450scc-ir localization shifted from the thecal layer to the interstitium. P450scc-ir cells appeared to increase in number midway through sex change. In sex-changed males, P450scc-ir cells were found in small clusters interspersed among spermatogenic lobules. These results demonstrate for the first time the ability of the gonad to produce potential steroidal mediators of gonadal restructuring throughout the sex change process.