Seasonal Male Reproductive Cycle of the Estuarine Snake Enhydris enhydris Schneider

The testis of Enhydris enhydris undergoes a definite seasonal reproductive cycle. Breeding takes place during the month of October, following which the testes regress. There is definite arrest of spermatogenesis till the next breeding season. Based on the histological examination of the seminiferous epithelium, the testicular activity is divided into four phases, recrudescent, breeding, degenerate and regressed. Recrudescence begins in the month of June. The testis becomes spermatogenically functional at the beginning of October. The testicular weight and gonado-somatic index show a gradual increase during the recrudescent phase (June -Sep) reaching the peak in the month of October. At the onset of degenerative phase the testicular weight and gonado-somatic index start decreasing. A corresponding seasonal variation is reflected in the ductus epididymidis and ductus deferens as observed from the epithelial cell height and the diameter of the respective ducts. On the other hand the sexual segment of kidney never reaches peak and does not indicate any seasonal cycle.