Evaluation of Leydig cell function and gonadotropin binding in unilateral and bilateral cryptorchidism: evidence for local control of Leydig cell function by the seminiferous tubule

The Leydig cell hypertrophy and loss of LU receptors that accompanies the surgical induction of bilateral cryptorchidism has been attributed to elevated serum LH levels. This study demon-strates that in unilaterally cryptorchid rats, the Leydig cell hypertrophy and loss of LH receptors is confined to the abdominal testis and there is no significant change in these parameters in the scrotal testis. These results and the failure of serum L.H levels to increase following unilateral cryptorchidism until 4 weeks, indicate that local factors within the cryptorchid testis must result in the changes in Leydig cell function. In addition to the loss of LU receptors and Leydig cell hyper-trophy, the cryptorchid testis showed a hyperresponsive testosterone response to hCG stimulation in vitro and a loss of FSH receptors whereas both of these parameters were normal in scrotal testes of the unilaterally cryptorchid rats