SEASONAL-CHANGES IN SPERMATOGENESIS AND ULTRASTRUCTURE OF DEVELOPING SPERMATIDS IN THE JAPANESE RAT SNAKE, ELAPHE-CLIMACOPHORA

Seasonal changes in spermatogenesis and the ultrastructure of developi ng spermatids in the Japanese rat snake, Elaphe climacophora, were obs erved by light and transmission electron microscopy. Spermatogenesis i n this species began in August, continued through October and ceased i n November. No spermatozoa were found during other periods. Japanese r at snakes mate from May to July, and spermatogenesis occurs after the mating season. Therefore, according to Girons' classification (1982), the reproduction of this species was classified as a postnuptial type. Although the morphological changes in developing spermatids during sp ermiogenesis in these snakes fundamentally resembled those in mammals, some unique features were detected. The most prominent characteristic of the developing spermatids was lipid-like structures. These structu res first appeared in early round spermatids, gradually increased in s ize and number, and, finally, aligned around the nucleus of mature spe rmatids. Although spermatozoa with lipid-like structures were released from the epithelium, stored spermatozoa in vas deferenses had none of these structures. Lipid-like structures that apparently separated fro m spermatozoa were scattered in the vas deferens. Prominent elongation of mitochondria was also remarkable in elongated spermatids.