THE SENSITIVITY OF VARIOUS GERM-CELL STAGES OF THE MALE MOUSE TO RADIATION INDUCED TRANSLOCATIONS

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Abstract
Adult male BALB/c mice were given whole body X-irradiation with 300 R. Directly after X-irradiation each male was mated to one virgin female of the same strain and received one fresh female per week during 9 weeks. The male F1 offspring was killed when mature and the testes removed and analysed for the presence of chromosome rearrangements at diakinesis — first metaphase stage of meiosis. Whereas no aberration was recorded among the 171 F1 ♀♀ from the control series, chromosomal abnormalities were observed in 41 F1 ♀♀ from the irradiated series. The incidence of males with aberrations was respectively 5.1% the first week, 10.4% the second week, 21.7% the third week, 2.2% the fourth week and 6.3% the fifth. No aberration was observed in the 129 F1 males sired between the sixth and ninth weeks. It may be concluded that irradiated spermatids yield approximately four times as many cases of aberration in viable F1 ♀♀ as do irradiated mature spermatozoa and about ten times as many as the most mature spermatocytes whereas no aberrations were recovered from irradiation of the spermatogonia. The most common aberrations found in the F1 males of the irradiated series were the reciprocal translocations.