Synthesis of steroids by echidna (Tachyglossus aculeatus) testis and the effects of gonadotrophin administration

Abstract

After administration of hCG [human chorionic gonadotropin] and PMSG [pregnant mare''s serum gonadotropin] to male echidnas (in non-breeding state) the testis to body weight ratio increased 3-fold and the diameter of the seminiferous tubules doubled, but spermatogenesis was not induced. The major conversion product of testicular homogenate with [4-14C]progesterone as substrate was 17.alpha.-hydroxyprogesterone (4% in untreated and 29% in treated echidnas). Testosterone (5%), androstenedione (16%) and 17.alpha.,20.beta.-dihydroxypregn-4-en-3-one (7%) were also obtained in gonadotropin-treated animals. In untreated animals these steroids were present in minor amounts (< 1%).