Sexual steroids in Salamandra salamandra (L.) during ontogeny.

In order to investigate the ontogeny of steroid secretions during the juvenile phase, sexual steroids were extracted and assayed after chromatographic separation in the gonads and plasma of male and female salamanders Salamandra salamandra L. at three characteristic postlarval stages. All specimens were collected in the wild. The immature stage is characterized, in the female, by high dihydrotestosterone (DHT) and 5 alpha-androstandiol levels, low progesterone concentration, and an absence of testosterone in the ovary. Just before sexual maturity a regular increase in plasma levels of estradiol and testosterone was observed. In the male, progesterone and DHT are at a relatively high level in the testis of the immature stage but concentrations decrease in subadults. In young adults, concentrations of progesterone are greater than they are in the immature animals. Sexual maturity is characterized by a large increase in testicular and plasma testosterone as well as a relative decrease in DHT, 5 alpha-diols, and estrone. The progesterone liberated into the plasma was negligible. Diols seem to play an important part in the ontogeny of sexual function.