イワガニの卵巣にみられる季節的変化 (海産無脊推動物の生殖腺の成熟に関する研究-6,7-)

概要

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The present paper deals with the seasonal changes in the ovary of the lined shore crab, Pachygrapsus crassipes, known as a common crab which is widely distributed in the rocky beaches of the Japanese Islands. The animals used in the present study were collected along the coast of Niigata City facing the Japan Sea, and the period of collection extended from April to November, 1969. By means of histological examinations and gono-somatic index, the seasonal changes found in the ovary were classified into six stages. These are: growth stage (April), vitellogenetic stage (May to early July), premature and mature stages (middle to late July), spawning stage (late July), and recovery stage (August to November). A small number of sudanophilic bodies were detected in the ooplasm of the young oocyte and after that, the yolk globules began to be deposited in the entire ooplasm with accompanied growth of the ovum. In the spent individual, the ovary was characterized by a considerable number of the ovulation scars, residual ova and developing ovarian stroma, intermingled with each other. Subsequently, the ovary reached the recovery stage as revealed by the absorption of the residual yolk by the stromatous tissue and several kinds of leucocytes. As some of the spent females with developing embryos in their abdominal flap have another set of mature ovary, it is assumed that these crabs can spawn twice during a single breeding season.
日本水産學會の論文