Spermatogenesis and epididymal sperm after scrotal gamma irradiation in adult rats.

Quantitative histologic evaluation was performed on the testes of albino rats exposed to scrotal gamma irradiation of 2.5 Gy and 10.0 Gy. The animals were sacrificed at 1, 2, 4, and 16 weeks posttreatment. As a result of irradiation, there was a gradual decrease in testicular weight. The seminiferous tubules of irradiated animals showed arrest of spermatogenesis, desquamation, vacuolization of germinal cells, and multinucleated giant cells. The extent of damage increased with posttreatment interval and with increasing dose. Counting of germinal cells at stage VII of the seminiferous epithelium revealed that the preleptotene spermatocyte is the most sensitive to radiation as compared to other cells. The number of epididymal sperm decreased, whereas the proportion of nonmotile and morphologically abnormal sperm increased following irradiation.