Studies of reproduction in the blue spiny lizard, Sceloporus cyanogenys Cope
Crisp, Thomas Mitchell
Talmage, Roy V.
Master of Arts
The blue spiny lizard, Sceloporus cyanogenys, an ovoviviparous lizard from Texas and Mexico was studied in order to contribute further information to the physiology of reproduction in reptiles. Seasonal Changes in gonadal microanatomy and the sex accessories could be demonstrated in this lizard as a criteria for the reproductive activity of testicular and ovarian tissue. The animal has a single breeding season which occurs during the winter months. Spermatogensis commences in August, followed immediately by a period of speriogenesis; producing nature sperm, which are shed into the epididymides and vas deferens prior to the time ovulation occurs in the female. Interstitial cells were seen to develop and regress with the waxing and waving of the sex accessories and secondary sexual characters. These sex accessories were demonstrated to be under the influence of the male sex hormone, testosterone. Ovogenesis and yoik deposition begins in Autumn; producing large eggs which are ovulated during mid-winter. A corpus luteum is formed from the old Graffian follicle. Stages in the developement of this structure are presented. Seasonal changes in the oviduct appear to be controlled by ovarian estrogens. Gestation lasts approximately four months, Apposition between fetuses and oviducal epithelium is loose. A demonstration of the ovoviviparous nature of the lizard indicates that there is no exchange between oviduct and fetuses, other than water and possibly gases. Mating behavior and parturition is described. The average number of young born to an adult female is 17.68. Mammalian gonadotrophins were incapable of inducing another reproductive cycle in females with quiescent ovaries; but oxytocin was able to facilitate parturition. A hypothesis for the ovoviviparous reproductive mechanism, and the winter breeding season, unique among reptiles, but found in S. cyanogenys, is proposed.