Laparotomized female tadpoles of Rana catesbeiana at TK stages X-XII, about 9 months old, were implanted intraperitoneally with empty capsules or capsules containing 4-hydroxyandrostenedione (4-OHA), known as an aromatase inhibitor in vertebrates. Histology, gonosomatic index, and secretions of estradiol (E2) and testosterone (T) of the ovaries were investigated. Three months after the treatment,
... [Show full abstract] histological examination revealed various degrees of sex reversal in the ovaries treated with 4-OHA and 79% (57 in 72) were transformed into testes. The ovaries of control tadpoles, however, displayed normal histological appearance. Radioimmunoassay showed that secretion of E2 was decreased while that of T was increased in 4-OHA treated ovaries. The gonosomatic index displayed a decline tendency from control females through experimental animals to untreated control males. These results indicated that activity of aromatase in the ovaries was inhibited by 4-OHA, resulting in accumulation of T which induced transformation of the ovaries into testes.