The process of sex change in the gobiid fish Trimma okinawae was investigated by gonad histology and immunohistochemistry of two steroidogenic enzymes. P450 cholesterol-side-chain-cleavage (P450scc) and 3β- hydroxysteroid dehydrogenase (3β-HSD). Irrespective of sexual phase, gonads comprised both ovarian and testicular tissues. Females changed sex to male within 7 days, reverting again to female over an 11-day period. In each sexual phase of the females, the 2nd (2DF-M) and 4th (4DF-M) day after the initiation of sex change to male, the males, and 2nd (2DM-F), 4th (4DM-F). and 6th (6DM-F) days after the initiation of reversion from male to female, histological observations were made. In the ovary during the female, 2DF-M, 4DF-M, and 6DM-F phases, both vitellogenic and previtellogenic oocytes were present, but only previtellogenic oocytes were found in the other phases. The testis contained sperm in all phases, but sperm ducts were not visible in the female phase. In the ovary, P450scc immunoreactivity of interstitial cells was strongly or moderately detected, although weak in the male phase. In contrast, P450scc immunoreactivity in thecal cells was found in all but the male and 2DM-F phases. 3β-HSD immunoreactive interstitial cells were detected in all phases, but only weakly so in the male and 2DM-F phases. 3β-HSD immunoreactive thecal cells were observed in all stages without the male and 2DM-F and 4DM-F phases. In the testis, moderate P450scc and 3β-HSD immunoreactivity was regularly found in the Leydig cells in all the phases. These results suggest that functional steroids including testosterone are produced in any sexual phases.
- Steroid production
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics