Histological study of the seminiferous epithelium in the Japanese rat snake, Elaphe climacophora: identification of spermatogonium.

To clarify the features of the seminiferous epithelium of the Japanese rat snake, Elaphe climacophora, the identification of spermatogonium and the examination of features of cell to cell junctions were performed in the present study. As for the identification, 5-bromo-2-deoxyuridine (BrdU) incorporation was examined immunohistochemically to mark spermatogonia. The seminiferous epithelium was observed throughout a year at the electron microscopic level. BrdU immunoreactivity was detected not only in the cells of the first layer of the seminiferous epithelium but also in the second and/or third layers. The cells immunoreactive in the first layer did not seem to attach to the basement membrane and were recognized throughout a year. To investigate cell to cell junctions, we performed actin filament detection by phalloidin staining. Distribution of actin filaments was different from that in mammalian species. At the ultrastructural level, Sertoli-Sertoli cell junctions were observed. Sertoli cells formed junctional complexes. Tight junctions were clearly found, but lacked the backing by actin filaments. These results indicate that the blood-testis barrier of the Japanese rat snake was structurally different from that of mammalian species. In conclusion, the seminiferous epithelium of the Japanese rat snake is intermediate in morphology between amphibians and mammals.

Seasonal changes in spermatogenesis and ultrastructure of developing spermatids in the Japanese rat snake, Elaphe climacophora.

Seasonal changes in spermatogenesis and the ultrastructure of developing spermatids in the Japanese rat snake, Elaphe climacophora, were observed by light and transmission electron microscopy. Spermatogenesis in this species began in August, continued through October and ceased in November. No spermatozoa were found during other periods. Japanese rat 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 spermiogenesis 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 structures first appeared in early round spermatids, gradually increased in size and number, and, finally, aligned around the nucleus of mature spermatids. 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 from spermatozoa were scattered in the vas deferens. Prominent elongation of mitochondria was also remarkable in elongated spermatids.

Studies on the venom components of the long-glanded coral snake, Maticora bivirgata.

The venom of the Asian long-glanded coral snake, Maticora bivirgata, was fractionated into five fractions, S1-S5, by passing through a Sephadex G-50 column. Fraction S2 contains two phospholipases A2, PLA2 I and PLA2 II, fraction S3 contains four cytotoxin homologues, maticotoxins A, C, D1 and D2, and fractions S4 and S5 contain a large amount (about 1 mg/specimen) of adenosine accompanied with smaller amounts of inosine and guanosine. The amino-terminal amino acid sequences of PLA2, I, PLA2 II and maticotoxin A suggest that Maticora bivirgata is closely related to Bungarinae, especially to genera Hemachatus and Naja.