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Histopathology of Unilateral Cryptorchidism

Defective mini-puberty inducing insufficient gonadotropin secretion is one of the most common causes of nonobstructive azoospermia in men suffering from congenital isolated unilateral or bilateral cryptorchidism. The aim of our study was to determine the risk for azoospermia by histologic criteria in a cohort of unilateral cryptorchid boys undergoing orchidopexy and bilateral testicular biopsy. We performed a retrospective analysis of data available in the library of the Cryptorchidism Research Institute, Liestal, Switzerland. Complete histological evaluations were available for 319 boys operated on for unilateral cryptorchidism with simultaneous biopsy of the contralateral descended testicle. The median age was 39 (5–192) months and 58 patients were <18 months of age. Forty-eight percent of undescended testis (UDT) and 21% of contralateral testis had no A dark (Ad) spermatogonia. Furthermore, in 11% of boys Ad spermatogonia were lacking in both testes. Positive correlation was found between the spermatogonia/tubule ratio of the UDT and contralateral testis (Spearman rank order correlation is 0.16, P = .003). The extent of alteration in the UDT correlated with the contralateral descended testis, indicating that unilateral cryptorchidism is a bilateral disease. Observed impaired transition from gonocytes into Ad spermatogonia indicates defective mini-puberty, providing one of explanations for azoospermia and infertility development in unilateral cryptorchid men.