STUDIES ON THE ANNUAL REPRODUCTIVE CYCLE OF THE SEA URCHIN AND THE ACID PHOSPHATASE ACTIVITY OF RELICT OVA

¹ Faculty of Science, Ochanomizu University, Bunkyo-ku, Tokyo 112
² Tateyama Marine Laboratory, Ochanomizu University, Tateyama-shi, Chiba 294-03, Japan

1. Specimens of the sea urchins, Anthocidaris crassispina and Hemicentrotus pulcherrimus, were collected each month, their ovaries were fixed and embedded in Epon 812, and thick sections were observed with the light microscope.

2. The sea urchin ovary has a clearly defined state in which nutrient globules are produced and stored in accessory cells. Especially in Hemicentrotus pulcherrimus, this state continued from May to November. The number of globules in the accessory cells fluctuated with the course of the reproductive cycle.

3. Toward the end of the breeding season, strong acid phosphatase activity was detected in the unshed (relict) ova as they degenerated, and numerous large mosaic globules containing cortical granules appeared in the accessory cells. It is proposed that the cytoplasm of relict ova is disrupted by the activity of their lysosomes.

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