Influence of Dose Rate on Radiation Effect on Fertility of Female Mice

Abstract

1) In an attempt to contribute to an understanding of unusual radiation sensitivity exhibited by the mammalian oocyte, a non-dividing cell, fertility experiments were carried out to determine the effect of dose rate (fractionation, different intensities of continuous radiation). 2) Fractionation markedly reduced damage to fertility; and division of dose into 10-r fractions was more effective in this respect than division into 25-r fractions. Continuously exposed females were even less affected in breeding performance than females which had received fractionated irradiation, and the lower the dose rate the smaller was the deleterious effect on fertility. In all groups, production, in terms of number of females casting litters, remained at maximum level until beginning of a sudden steep decline that ended in sterility. It is for this reason that some experiments of other investigators, who have measured performance only in terms of the first postirradiation litter, have failed to show similar dose-rate effects. 3) The results indicate that some repair of radiation damage to oocytes can occur, and that repair is greater at lower dose rates.