Conversion of progesterone to androsterone by testicular tissue at different stages of maturation

Changes in the in vitro capacity to convert progesterone to androsterone were studied in testes of rats of varying ages from birth to maturity. No androsterone was detected in incubates of testicular tissue from 1-day-old rats. However, with increase in age the capacity to convert progesterone to androsterone appeared and progressively increased, reaching a peak in testes of 20-day-old rats. Then it gradually diminished with age, and in 90-day-old rats it again fell to almost undetectible levels. A definite relationship was observed during the course of testicular development between the capacity to convert progesterone to androsterone or testosterone, the relationship being inverse. The physiologic implication of this phenomenon and the question whether androsterone formed in these testicular incubates is a metabolic product of testosterone remains to be elucidated.