Influence of Age, Body Weight, and Sex on Susceptibility of Mice to the Lethal Effects of X-radiation.

Summary and Conclusions (1) The age at which mice are irradiated profoundly alters their resistance to a single exposure of whole body irradiation. Mortality is low after irradiation at 1 and 15 days of age, very high at 30 days, and decreases rapidly with increasing age thereafter. The possible mechanisms of this effect are discussed. (2) The response of mice to whole body irradiation is not related to body weight except insofar as weight reflects a particular age range. (3) In general, sex appears to exert no significant influence on the capacity of mice to withstand whole body irradiation.