Germ cell apoptosis in undescended testis: the origin of its impaired spermatogenesis in the TS inbred rat.

PURPOSE: Undescended testis is one of the most important congenital anomalies in male urogenital organs that may cause male infertility. We examined the process of spermatogenesis of TS inbred rats, of which approximately 70% of male newborns have congenital undescended testes. MATERIALS AND METHODS: Unilaterally affected animals at ages 4, 6 and 8 weeks were analyzed in this study. Histopathological evaluation of spermatogenesis was performed by periodic acid-Schiff-hematoxylin staining. To elucidate the pathophysiology of seminiferous tubule damage germ cell apoptosis was assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling and electron microscopy. Four animals per group were used for staining and nick end-labeling. RESULTS: Testicular weight significantly decreased on the affected side at ages 6 and 8 weeks. Impaired spermatogenesis was observed as early as age 4 weeks. Germ cell apoptosis was significantly more frequent on the affected side in all age groups with the most prominent incidence at age 6 weeks. Most apoptotic germ cells were considered spermatocytes. Electron microscopy revealed apoptosis of spermatocytes with condensation of chromatins and agglutination of cytoplasmic contents. CONCLUSIONS: This study suggests the efficacy of early intervention in patients with undescended testes.