REPRODUCTIVE ACTIVITY AND PLASMA ANDROGEN CONCENTRATIONS IN THE MALE OF RANA-DALMATINA

Reproductive activity (spermatogenesis, testis and fat-body weight, thumpad) is related to environmental factors and plasma androgen levels in the male of Rana dalmatina. The population studied, living at 1000 m a.s.l., showed a markedly discontinuous spermatogenetic cycle. From November to February, spermatogenesis stopped completely. Spermiation occurred from late February to late March. In May, there was recovery of spermatogenesis. The mating season and ovipositions took place from the end of February to late March or early April, when environmental temperatures increase and the pool where this species reproduces thaws. Significant seasonal variations were observed in the testis and, fat-body weight, thumpad epithelium, and plasma testosterone but not in plasma androstenedione. Plasma testosterone peaked in February, two months after the maximum development of nuptial callosity; however, there was a positive correlation between these two characters, which was not observed, instead, between nuptial callosity and plasma androstenedione levels. Finally, an explanation is provided for the occurrence of developed interstitial tissue after the reproductive season, when androgen (both T and A) levels in the plasma are at the minimum, and the nuptial callosity is completely regressed.