Abstract
(1) A proper appreciation of ovarian damage by radiation is possible only if enough time is given for the damage to develop. Simple fertility is a less adequate measure of damage than reproductive capacity–the total number of young produced in the reproductive life-span. In C57BL mice this is halved by a single dose of 25 r of x-rays and by about 80 r of gamma-rays given at 2·2 r daily. (2) The high radiosensitivity of the ovary and the variation of somatic ovarian damage with dose-rate need to be taken into account when interpreting experimental results obtained in the female mouse, especially in studies of the effect of dose-rate on the frequency of radiation-induced mutations. It is possible that more attention should be given to somatic ovarian sensitivity when considering radiation hazards.