In vitro steroid production in the postovulatory follicles of the amago salmon, Oncorhynchus rhodurus, in response to salmon gonadotropin.

Partially purified chinook salmon gonadotropin (SG-G100) was used to investigate estradiol-17 beta and progesterone production in vitro in the isolated postovulatory follicles of the amago salmon, Oncorhynchus rhodurus, at varying intervals after ovulation. Chinook salmon gonadotropin stimulated progesterone production in vitro in the young postovulatory follicles, but not in the older ones. In contrast, estradiol-17 beta production was not stimulated in either young or older postovulatory follicles. Morphological observations indicate that young postovulatory follicles are more glandular than older ones. Thus, it is concluded that the young postovulatory follicles of the amago salmon are steroidogenic.