Current concepts and controversies in undescended testes.

Cryptorchidism, or undescended testis, is the most common genital anomaly identified at birth in males that continues to challenge the pediatric specialist. The last two decades have seen rapid improvements in understanding the complex mechanisms underlying the genesis of cryptorchidism. Yet, despite years of study, answers to questions relating to controversies surrounding undescended testes remain elusive. This article presents an overview of the controversies and current understanding of this challenging problem.