Ovarian steroid levels in Salamandra salamandra infraimmaculata during the reproductive cycle.

Gonadal steroid levels were determined in the ovary of Salamandra salamandra infraimmaculata during the reproductive cycle in populations from a xeric region in northern Israel. Varying proportions of previtellogenic and vitellogenic oocytes were present throughout the year, and mature oocytes were present in winter and spring. The numbers of mature oocytes were greater between December and April, after parturition. The levels of 17 beta-estradiol and testosterone rose during oocyte vitellogenesis and maturation. Levels of progesterone and 17 alpha-hydroxy progesterone appeared to be related to the level of vitellogenesis. Gravid females contained greater quantities of all four steroids than did nongravid females.