Seasonal variations of androgens, estrogens, and progesterone in the different lobules of the testis and in the plasma of Salamandra salamandra.

Progesterone, 4-androstenedione, testosterone, dihydrotestosterone, 5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol), 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol), estrone, and estradiol levels were determined by radioimmunoassay in the different lobules of the testis of Salamandra salamandra throughout the year according to the seasonal cycle. 3 beta-diol levels were not detectable. High levels of steroids were found in the grandular tissue (enlarged pericystic cells after spermiation) and large variations were showed for progesterone, 4-androstenedione, testosterone, 3 alpha-diol, and estrone. In the mature lobule (formed by cysts with mature spermatozoa), only testosterone showed seasonal variations and in the immature lobule (with early stages of meiosis), 3 alpha-diol showed fluctuations. The major estrogen found in the testis of Salamandra was estrone; estradiol stayed at a low level throughout the cycle. The steroids fluctuation seems to be related to the histological evolution of the testis throughout the cycle. The present data were the first on steroid seasonal variations in the testis of an urodele.