Dynamics of ovarian follicles in Tupinambis merianae lizards

Abstract

Follicular dynamics of Tupinambis merianae lizards was analyzed by means of ultrasound examination and radio frequency identification, during three consecutive reproductive periods, both in reproduction and in sexual isolation. Series of follicular development which ended in ovulation, and series of follicular development without ovulation, followed by a regression process, were observed, as well as a combination of both. Ovulation was found to be strongly dependent on mating consummation. In 34% of the cases in which follicular development ended with ovulation, and hence oviposition, follicles showed a steady and uniform growth up to the periovulatory period, also acquiring a mild echogenicity. In the absence of ovulation (66% of cases), follicular development showed two patterns: a short and a long-term anovulatory follicular cycle. In the first pattern, follicles showed limited growth and a non-echoic aspect, which suggests a previtellogenic condition. In the second pattern, follicles exhibited a growth and echogenicity similar to periovulatory ones, presumably attaining a vitellogenic stage. In addition, follicular development in reproducing females was superior to that of sexually isolated females. Follicular development, ovulation, and follicular regression appeared to constitute generalized events affecting most, if not all, of the recruited follicles.