title: Evidence for a decrease in aromatase activity in the ovarian granulosa cells of amago salmon (Oncorhynchus rhodurus) associated with final oocyte maturation.
abstract: Aromatase activity in the isolated granulosa layers of amago salmon (Oncorhynchus rhodurus) ovarian follicles was examined during the course of vitellogenesis and final oocyte maturation and ovulation. Estradiol-17 beta production by isolated granulosa layers incubated with exogenous testosterone increased during the period of vitellogenesis to reach a peak in late vitellogenesis, and then declined rapidly, in association with the ability of the oocyte to mature in response to partially purified salmon gonadotropin (SG-G100). Extremely low levels of estradiol-17 beta were produced by granulosa layers from follicles which had undergone final oocyte maturation in vivo and by post-ovulatory follicles. SG-G100 had no discernible effect on estradiol-17 beta production. These results are discussed in relation to other studies on the endocrine control of steroidogenesis in this species.
mesh_terms: D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D006062:Gonadotropins / Q000494:pharmacology; D006107:Granulosa Cells / Q000201:enzymology* / Q000378:metabolism; D009865:Oocytes / Q000254:growth & development*; D010088:Oxidoreductases / Q000378:metabolism*; D012474:Salmon / Q000502:physiology*; D013739:Testosterone / Q000378:metabolism
chemical_list: D006062:Gonadotropins; C016844:salmon gonadotropin; D013739:Testosterone; D004958:Estradiol; D010088:Oxidoreductases; D001141:Aromatase