Early signs of Sertoli and Leydig cell dysfunction in the abdominal testes of immature unilaterally cryptorchid rats.

Testicular descent was prevented unilaterally by cutting the gubernaculum testis of newborn rats. When 20 days old unilaterally cryptorchid rats were injected intraperitoneally with 2 micrograms bFSH per gram body weight and killed 6 h later when testicular testosterone (T) and oestradiol (E2) concentrations were determined. The increase in E2 was subnormal in abdominal testes. In 18-day-old unilaterally cryptorchid rats the efferent ducts were ligated bilaterally, and the rats were killed 48 h later. The weight increase, due to accumulation of seminiferous tubule fluid, was significantly greater in the abdominal testes. In contrast, the ABP content of the abdominal epididymis was subnormal in 20-day-old unilaterally cryptorchid rats. Unilateral orchidectomy was performed in 16-day-old unilaterally cryptorchid rats and at 20 days of age intratesticular T and E2, and plasma FSH and LH concentrations were determined and compared to that in 20-day-old control unilaterally cryptorchid rats. Removal of an abdominal testis resulted in increased plasma FSH and intratesticular E2, whereas plasma levels of LH and intratesticular levels of T were unaffected. Removal of a scrotal testis resulted in increased plasma FSH and LH coupled with increased intratesticular T and E2. Rats with a single abdominal testis had higher plasma FSH and LH and intratesticular T, but similar intratesticular E2, than rats with a single scrotal testis. It is concluded that Sertoli and Leydig cell function are influenced by cryptorchidism at a stage when the temperature difference, and the morphological differences between the testes are very discrete.