メダカに於ける第一次及び第二次性特徴の關係 : II.卵巣を除去せるメダカに精巣の移植實驗

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In Oryzias latipes, the male differs from the female in having the bony processes on the rays of the anal fin. On transplanting the testis into the ovariotomized female, the fish forms the processes on the anal fin-rays which are characteristic to the male. When the testis is grafted during the breeding season of this fish (spring and summer), the processes appear in five to seven weeks after the operation; while grafted out of the breeding season (autumn and winter), the appearance of the processes is delayed until the beginning of the following breeding season. Therefore, two things can be concluded (1) that there exists a correlation between the testis and the male processes in Oryzias latipes and (2) that the influence of the testis is active only in the breeding season. On examining the grafted testes microscopically, it is found that the spermatogenesis is somewhat retarded. In a single case, however, a testis containing oocyte-like cells is found. But the effect of this testis upon the secondary sexual characters does not differ least from that of the other testes. Since the apparition of such pseudoocytes in the normal testis is frequently met with, one of such testes must accidentally have been used as a graft. Even when the removal of the ovary is not complete, the activity of the transplanted testis to produce the male processes does not seem to suffer any inhibitory influences from the part of the residual ovary; in other word socalled "hormone antagonism" between both gonads is not abserved in these cases. In some operated females, the male processes failed to be formed. Autopsy reveals that in these individuals the grafted gonads suffered degeneration and their cavities were invaded by the connective-tissue cells.
社団法人日本動物学会の論文
1936-03-15

メダカに於ける第一次及び第二次性特徴の關係 : II.卵巣を除去せるメダカに精巣の移植實驗

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