[Mutagenic effect of radiation on mice subjected to gamma irradiation during the embryonic period. I. Frequency of reciprocal translocations in the spermatocytes of mice subjected to gamma-irradiation at different stages of embryogenesis].

The frequency of reciprocal translocations was investigated in spermatocytes of mice gamma-irradiated at doses of 100 or 200 r at 4,5; 8,5; 10,5; 11,5 and 13,5 days of embryonic development, and in spermatocytes of adult males whose spermatogonia were irradiated. The cytological analysis of 41 males that were irradiated at a dose of 200 r at 4,5 days of embryogenesis showed that 2 males had a high frequency of reciprocal translocations in both testes (on the average 20,6 and 28,8%). In the testes of other males of this group translocations were not detected. It is highly probably that the testes of these 2 males were heterozygous for reciprocal translocations. The yield of reciprocal translocations in spermatocytes of males irradiated at 8,5--13,5 days of embryogenesis was very low, and was only 0,67 +/- 0,2 x 10(-5) on the average per 1 r per cell, whereas for adult mice it was 12,5 +/- 3,0 x 10(5) per 1 r per cell.