The Influence of Age on Reproductive Capacity in C57bl Mice

Summary. The influence of age on fertility was investigated in male and female C57/BL Icrf at mice, ranging in age from 1½ to 30 months. In males, the number of litters sired declined after about 24 months but there was no significant change in litter size. Most mice over 24 months old were sterile. The oldest male to sire a litter was 31 months old. The litter size in females followed the accepted pattern, declining from about 8 months: most mice were sterile by 12 months and the oldest mouse to produce a litter was 16 months old.