魚の生体外排卵に関する生物学的研究-IV. : ステロイドによるメダカの生体外排卵について

概要

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The present investigation was undertaken to clarify the effects of steroids on ovulation in vitro of the Oryzias oocytes. In the experiments, at 10.00 a.m. the synergistic action of progesterone and HCG was shown, but in other cases where only steroids or both steroids and HCG were used the incubated oocytes did not show any markedly induced ovulation. Hydrocortisone at 5.00 p.m. was very effective in inducing ovulation. Other steroids were also effective, but their potencies for ovulation were not as high as hydrocortisone. At 11.00 p.m. all steroids used in this study were very effective in inducing ovulation in vitro, but the oocytes also showed best response to 1 μg/ml of hydrocortisone. These observations suggest that induction of ovulation in vitro of the Oryzias oocytes with steroids vary markedly with the initiated hour of incubation. Furthermore, the role of steroids in the ovulation of Oryzias latipes has been discussed.