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Gametogenesis and reproductive cycle of the gastropod mollusk acmaea pallida


, : Gametogenesis and reproductive cycle of the gastropod mollusk acmaea pallida. Biologiya Morya (Vladivostok) (1): 47-52

The gametogenesis and reproductive cycle of the limpet Acmaea pallida were studied by histological methods. The formation of the gonads occurs at the shell length about 7-8 mm, which apparently corresponds to the second year of life. Individuals are capable of spawning at the shell length over 30 mm, which corresponds to the fourth year of life. Spawning takes place in September. There is no resting period after spawning because gametogenesis and resorption of unreleased gametes occur simultaneously. Many groups of unusual accessory cells are present in the female gonads at this time. The development of the oocyte is solitary. During vitellogenesis the oocyte is surrounded by thin follicular cells. Active vitellogenesis begins in early spring. Mature oocytes covered by a thick protein-polysaccharide membrane are found in the lumens of the ovarian tubules by the end of summer. Meiosis begins after the eggs have been released and stops at metaphase 1. After the penetration of spermatozoid meiotic divisions are completed by the formation of residual bodies. Released eggs are red in color, 200 .mu.m in diameter and covered by a transplant membrane 25 .mu.m thick. Fecundity of A. pallida is about 500,000 eggs per female.

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