Hormones and the Sex Ducts and Sex Accessory Structures of Reptiles

Publisher Summary This chapter reviews the reproductive ducts of male and oviparous female reptiles. Sperm ducts consist of the rete testis, efferent ductules, epididymis, and vas deferens. An accessory organ, the renal sex segment, is present in squamate reptiles. The entire sperm duct system is under androgen control. Male sex hormones stimulate epididymal secretions that may be involved in sperm maturation. Oviducts may be subdivided into the infundibulum, uterine tube, isthmus, uterus, and vagina. The isthmus and uterine tube regions are absent in squamate reptiles. Female sex hormones stimulate the development of tubuloalveolar glands in the walls of the uterine tube and uterus. Progesterone reduces contractility of the uterus, and AVT, a neurohypophysial hormone, together with PGF2a promote uterine contractions. Oviposition is accomplished by interactions of the above hormones tempered by adrenergic innervation. Sperm may be stored in the epididymis of the male or in the tubuloalveolar glands of the female for long periods of time. Such storage is influenced by estrogenic hormones and has implications for strategies of life history and evolutionary ecology.