Abstract
When mated, unisexually-reared female rats produced a significant excess of females in their litters, while males predominated significantly in litters produced by bisexually-reared females. The percentage of female offspring produced by both types of females declined with successive litters. 1st litter offspring of unisexually-reared females were significantly heavier, and generally less variable in weight at weaning than the comparable offspring of bisexually-reared females, a difference which was apparently maternally-induced. These differences in weaning bodyweight disappeared, or were reversed in favour of the offspring of bisexually-reared females, in 2nd litters.