Evaluation of Radiation-induced Apoptosis in Seminiferous Tubule of ICR Mouse after Gamma

cells by radiation and other toxicants has recently been attributed to apoptosis, but a critical evalua-tion of the presence of the different features of apoptosis in each epithelial stage has not been performed. In this study, mouse testes exposed to radiation were examined by light microscopy and terminal transferase-mediated end labeling (TUNEL) with periodic acid-Schiff (PAS) stains to de-termine whether the cells were apoptotic according to several criteria. Apoptosis was easily recog-nized by the presence of peroxidase-stained, entirely apoptotic bodies. In the TUNEL-positive cells or bodies, the stained products correlated precisely with the typical morphologic characteristics of apop-tosis as seen at the light microscopic level. The changes that occurred from 0 to 24 hours after expos-ing the mice to 2 Gy of gamma-rays (2 Gy/min) were examined. The numbers of apoptotic cells reached a peak at 12 hours after irradiation and then declined. The mice that received 0-8 Gy of gam-ma-rays were examined 8 hours after irradiation. Dose-response relationships were generated for each stage of the epithelial cycle by counting TUNEL-positive cells. The dose-response curves were line-ar-quadratic [y=(-0.014±0.009)D 2 +(0.31±0.697)D+0.3575. Where y=the number of apoptotic cells pe