The male reproductive cycle of the Dice Snake, Natrix tessellata (Serpentes: Colubridae), in northern Iran

摘要

The Dice Snake, Natrix tessellata, is a non-venomous oviparous and diurnal snake whose distribution extends across Iran except for the south-eastern regions. We studied the spermatogenic cycle of this species in Mazandaran Province between April and November 2012. The specimens were collected from four stations in Sari where 57 adult males were investigated morphometrically and histologically. The testes included 24-192 seminiferous tubules. The length of the testes varied between 8.07 and 36.70 mm and the diameter of the tunica albuginea between 7 and 42 microns. The results indicated that spermatogenesis is composed of three phases: an active phase from May to September, a transitional phase in October, and a silent and regenerative phase from November to March. Spermatogenesis began in late May and increased in mid-August and early September, reduced in late September and October, and stopped in early November completely. The spermatogenic cycle can be characterised as aestival.