Regeneration of Gonads in Plecoglossus altivelis after Spawning Season

Abstract

1. The appearance and fate of the germ cells in the gonads of the Ayu fish obtained during and after their spawning season in the rivers and the pond were studied.
2. In the river Tamagawa, the female fish after the spawning season could be obtained until in the middle of June, while the male fish could not be obtained after the last October, except only two which were got until December (cf. table 1).
3. In the female fish of the river Tamagawa, there was no formation of a new crop of germ cells in the gonads, while it was observed in the male.
4. In the fish obtained at Unagiike pond, the new crop of germ cells was found to form in the gonads of both sexes after the spawning season.