Fertility in cryptorchidism: further development of an experimental model.

Further development of an experimental model for evaluating fertility in cryptorchidism led to studies of unilateral cryptorchidism, endocrinological cryptorchidism, and the effects of treatment. The results demonstrate that rats with unilateral mechanical cryptorchidism have a significant diminution in the ability to impregnate females (impregnation rate, 45%) when compared with sham-operated controls (84%) and rats undergoing unilateral orchiectomy (88%). In addition, we demonstrated that lower doses of estradiol caused cryptorchidism and resulted in infertility of approximately the same degree as higher doses (impregnation rates, 18% and 0%, respectively), but avoided obvious side effects. Treatment of estradiol-induced cryptorchidism with human chorionic gonadotropin resulted in testicular descent, but did not significantly improve the ability to bear offspring (10% with hCG vs. 0% without). Surgical orchiopexy after surgically induce mechanical cryptorchidism resulted in improved fertility (30% vs. 0%); however, the improvement was still significantly less than the control rate. In summary, this experimental model demonstrates the effects of various aspects of cryptorchidism and its treatment on fertility and can easily be adapted to evaluate important clinical problems.