種々の生殖腺刺激ホルモンおよびステロイドホルモンによるアマゴOncorhynchus rhodurusとニジマスSalmo gairderiのin vitro卵成熟誘起効果

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The effects of mammalian and salmon gonadotropins and various steroid hormones on germinal vesicle breakdown (GVBD) were investigated in amago salmon Oncorhynchus rhodurus and rainbow trout Salmo gairdnri oocyte using an in vitro incubation technique. Partially purified chinook salmon gonadotropin (SG-G 100) was found to be effective in inducing GVBD in the folliculated oocytes of both amago salmon and rainbow trout, thus indicating that the ovarian follicles are the major sites of gonadotropin action; however, none of the mammalian gonadotropins induced GVBD. Progestational steroids were shown to be much more effective than corticosteroids in inducing GVBD in these fishes; of the steroids, 17α-hydroxy-20β-dihydroprogesterone was the most potent GVBD inducer in rainbow trout. In both amago salmon and rainbow trout, testosterone was less effective, while estradiol-17β was ineffective. However, in vitro ovulation never occurred following in vitro gonadotropin- or steroid-stimulated GVBD, thus suggesting that oocyte maturation and ovulation are controlled by two different hormonal mechanisms.
日本水産學會の論文