Effect of size and sex ration of litter on the sexual maturation of female mice

The relationships between the size and sex composition of the litter and puberty in female mice were investigated. Both factors significantly affected the age of first vaginal oestrus; litter size accounted for 22% of the total variation in age at puberty, and litter sex composition for 8%. When no males or only one male was present in litters of 10 young the females matured significantly earlier than when two or more males were present.