Life span and tumours in the first-generation offspring of the gamma-irradiated male mouse.

C57BL/6 male mice were exposed to 3 Gy 60Co gamma-rays and mated with unirradiated females after 15 days to produce F1 progeny produced following irradiation of the spermatids. After weaning the offsprings were allowed to live their normal life span. The mean litter size of the irradiated group significantly decreased from 7.1 to 4.9 (p < 0.01), but the sex ratio was not altered by the irradiation. No significant differences in the survival curve and mean life-span between the irradiated and control groups were noted. The only radiation effect in tumour incidence was a decrease of histiocytic sarcoma in female offspring of irradiated males. Except for this, there were no significant differences between the irradiated group and the control group in the incidence or age distribution of tumours.