Dose-Response Relationship for Translocations Induced by X-Irradiation in Spermatogonia of Mice

Abstract

Male BALB/c mice received local irradiation to the testes with exposures of 250, 500, 750, 1000, or 1250 R of x-rays. Thirty weeks after treatment, the mice were killed, the testes were removed and used for cytological examination of spermatocytes. The chromosome rearrangements identified cytologically were all reciprocal translocations. The percentage of abnormal cells increases from 4.50% after 250 R to 7.29% after 500 R and confirms the linearity of the dose-response relationship up to 600 R. Reduction in the yield of translocations was recorded after higher x-ray doses presumably because of germinal selection. The x-ray kinetic data suggests that, at the dose levels used, the major proportion of chromosome rearrangements was produced by the passage of only one electron track and not by the interaction of two.