Life and Medical Sciences
Cell & Developmental Biology
Wiley InterScience Backfile Collection 1832-2000
The clam Mya differs from other pelecypods which have been investigated in this respect in having most of the reserve nutritive materials formed within the vacuolated follicle cells of the gonads instead of within the very limited amount of mesenchymatous connective tissue of the visceral mass. The profusely branching tubular gonads originate from two groups of primordial germ cells situated in the position of the future genital apertures. The germinal primordia soon become differentiated into two types of nuclei, one of which becomes associated with the large, vacuolated follicle cells, which form the principal volume of the gonadal tissue, while the other type proliferates to form the primary gonia which become widely scattered along the walls of each alveolus.There is much degeneration and cytolysis during gametogenesis in both sexes, with the accumulation of characteristic inclusions within the follicle cells. Atypical spermatogenesis followed by cytolysis occurs throughout the year but the normal method only in preparation for spawning. No evidence of protandry or change of sex was obtained; only three hermaphrodites were found in the examination of more than 1000 individuals.
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