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 con-secutive reproductive periods, both in reproduction and in sexual isolation. Series of follicular development which ended in ovulation, and series of follicular develop-ment 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 con-summation. In 34 % of the cases in which follicular development ended with ovula-tion, 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, presum-ably attaining a vitellogenic stage. In addition, follicular development in reproduc-ing 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