Metabolism of testosterone by isolated semiferous tubules and interstitial tissue of rat testes.

In prepubertal rat testes the main metabolisation of testosterone, which consists in 5alpha-reduction, is located predominantly in the Leydig-cells and is low in the seminiferous tubules. In adult rats, this metabolisation pattern has shifted to increased 7alpha-hydroxylation which is located mainly in the Leydig-cells, while 5alpha-reduction is performed in the seminiferous tubules. After prolonged treatment with HCG the 7alpha-hydroxylase activity in the Leydig-cells is strongly depressed while the metabolism of the seminiferous tubules is not influenced.