Abnormal Sperm in Crab-eating Monkeys After Acute Testicular γ-Irradiation

Abstract

The sperm of crab-eating monkeys (Macaca fascicularis) were examined every two weeks after their testes were acutely irradiated with 1, 2 and 3 Gy using ¹³⁷Cs γ-rays at a dose rate of 0.25 Gy/min. The spontaneous incidence of abnormal head shapes of their sperm was estimated to be 0.80%, with a range of 0.33% to 1.57%. The frequencies of abnormal sperm heads clearly increased with increasing dose and varied with time post irradiation. The maximum γ-ray effects were observed after 8 weeks in the 1 and 2-Gyirradiated animals and at 6 weeks in the animals exposed to 3 Gy. The results suggested that early spermatocytes and late spermatogonia are the cells most sensitive to radiation-induced abnormalities of the sperm heads. The peak yields were 5.4% at 1 Gy, 13.1% at 2 Gy and 14.9% at 3 Gy. The dose-response relationship for induction of sperm abnormalities fitted well to the linear equation, Y = 0.24 + 6.15D, when the testes of the crab-eating monkeys were irradiated with doses below 2 Gy. Above 2 Gy, the rates of induction of sperm abnormalities seemed to decrease.