アゴハゼChasmichthys dolichognathusの生殖年周期〔魚類の生殖リズムに関する研究-7-〕

概要

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The tidepool-living goby Chasmichthys dolichognathus was collected around Arasaki in Kanagawa Prefecture at intervals of about a month from March 1980 to July 1982. Seasonal changes in the GSI and the gonadal histology indicated that their spawning season extended from February to May. During this period, females with empty follicles in their ovaries were often observed. In female fish, the GSI increased rapidly in December with concomitant accumulation of yolk in the oocytes. In June it decreased suddenly, as the oocytes underwent regression. The seasonal change of GSI in males was similar to that in females, although testicular lobules started to develop in October and sperms appeared in December. The rapid changes in the GSI suggest that water temperature plays an important role in both initiation and termination of their spwaning season. Hepatic cells of females showed a strong affinity to hematoxyline from November to May, while the cells were weakly stained in the other period. Those of males did not exhibit such an apparent seasonal change. In mature fish, a major part of proximal pars distalis in the pituitary gland consisted of gonadotrophs which had showed a strong affinity to aldehyde-thionine. Those of immature fish, however, were less in number and weakly stained.