In vitro estradiol-17 beta and testosterone production by ovarian follicles of the goldfish, Carassius auratus.

In vitro production of estradiol-17 beta and testosterone by ovarian follicles of goldfish (Carassius auratus) at different developmental stages in response to human chorionic gonadotropin (HCG) was examined using 18-hr incubations. The vitellogenic follicles (primary and secondary yolk stage) produced estradiol-17 beta in response to HCG; follicles at the secondary yolk stage produced about five times more estradiol-17 beta than the primary yolk stage follicles. However, tertiary yolk stage follicles, which could be induced to mature in vitro by HCG treatment, did not produce estradiol-17 beta. HCG also stimulated testosterone production by follicles at all stages of development; maximal production was observed in tertiary yolk stage follicles. An indirect assessment of aromatase activity at each stage was made. Vitellogenic follicles (primary and secondary yolk stage) produced estradiol-17 beta when incubated with testosterone, the larger follicles producing about three times more estradiol-17 beta. Only low levels of estradiol-17 beta were produced by tertiary yolk stage follicles. Addition of HCG to primary yolk stage follicles slightly but significantly enhanced estradiol-17 beta production; however, no enhancement was seen with secondary and tertiary stage follicles. These results suggest that the decrease in estradiol-17 beta production in tertiary yolk stage follicles may be partly due to a decrease of aromatase activity at this stage.