Delta-ray-induced reciprocal translocations in spermatogonia of the crab-eating monkey (Macaca fascicularis).

The yield of translocations induced by delta-rays in the crab-eating monkey (Macaca fascicularis) spermatogonia were studied by cytological analysis in spermatocytes derived from them. The frequencies of translocations were 0.09% at 0 Gy, 1.9% at 1 Gy, 2.5% at 2 Gy and 1.3% at 3 Gy, showing a humped dose-response curve with a peak yield around 2 Gy. No remarkable inter-seasonal or inter-animal variations in the induction of translocation were observed. The frequencies in the crab-eating monkey were significantly higher than those in the same Macaca genus, the rhesus monkey (Macaca mulatta) (van Buul, 1976, 1980). This inter-species difference in radiosensitivity might be affected by the condition of spermatogonial stem cells at the time of exposure to radiation, depending on the seasonal change in spermatogenetic activity.