LONG-TERM REPRODUCTIVE PERFORMANCE OF FEMALE MICE

Summary. The breeding performance of normal intact female mice (two-ovary females) was compared with that of female mice from which one or other ovary had been surgically removed before sexual maturity (one-ovary females). The comparison was continued throughout the reproductive lives of the females. The one-ovary mice produced fewer litters, and stopped breeding at an earlier age, than did the intact controls. The total number of young produced per female in the one-ovary group was 56 % of the total number produced per female in the two-ovary group. Each female was killed when it had failed to produce a litter for 16 weeks, since its reproductive life was then judged to have ended. However, nearly half the females were or had recently been pregnant when killed. The weight at autopsy of the surviving ovary in the one-ovary females was not significantly less than the combined weight of both ovaries in the two-ovary females. Histological observations of the ovaries and uteri of the aged females are described.