Cell death peaked within 72 h of treatment [40]. 0.2 Gy of γray depleted approximately 22% of type A spermatogonia 15 h after irradiation. 1 Gy of Xray resulted in loss of more than 70% of type A spermatogonia by 72 h after irradiation, whereas nearly complete depletion of type B spermatogonia was observed 36 h after irradiation