Radiosensitivity with Respect to the Estrous Cycle in the Mouse

Abstract

Since male mice of any species have proved to be more reliable than females in radiation lethality studies, this study reports the reactions of female CF1 mice in each of the 3 major phases of estrus, when exposed to the male LD/50/30-day dose of whole body X-radiation. Males are more radiosensitive than are females in any stage of estrus. Females in estrus are the most radioresistant, those in diestrus the most radiosensitive. Females in pre- and post-estrus were classified together, due to the short duration of the phase and the vaginal smear similarity. However, the variability in this combined group suggests that the pre-estrus may be the most radioresistant of all stages, by virtue of the high estrogen production at that time. It is postulated that estrogens, plus correlated endocrine and hydration changes may be responsible for the wide fluctuation in female radiosensitivity.