Ovarian development and sex steroid hormones during the reproductive cycle of Podarcis s. sicula Raf.

Variations in ovary weight and seasonal changes in plasma androgens, 17 beta-estradiol and progesterone have been studied during the reproductive cycle of female Podarcis s. sicula Raf. Adult female Podarcis were captured in the surroundings of Naples during the years 1988 and 1989. Ten lizards were sampled monthly (except in February, August, October and December). Ovaries and oviducts were submitted to morphological examination, and in the blood samples androgens, 17 beta-estradiol and progesterone were assessed by the radioimmunoassay (RIA) method. Ovary weight, expressed as the gonadosomatic index (GSI), presented two statistically significant peak values in April and June, related to the ovulatory waves observed in this study. Several shelled oocytes were also found in the oviducts in this period. Progesterone titers mirrored the modifications of GSI and a very significant correlation (p less than 0.001) between the two parameters can be ascertained. Androgens increased in early spring, peaked in April, and low levels of androgens were found in September and during the winter months. Estradiol titers reached the peak values in March, and, after a sharp decrease in April, remained high until the winter months. The results reported here substantiate the periovulatory changes of the three major gonadal steroids during the annual ovarian cycle of Podarcis s. sicula.