Relationship between litter size and the development of the rat brain during the suckling period

The brain of 23-day-old rats raised in small, large, and control litters is studied. In large litters, body weight is significantly lower and the relative mass of the brain is higher than in controls. In small litters, body weight of males and females is considerably higher, while the relative mass of the brain is lower; in females, the absolute mass of the brain and of the left hemisphere is significantly higher. In rats of both sexes from small litters the weight of body, brain, and hemisphere is higher than in rats from large litters. In addition, in males from small litters the neurons of layer V are larger. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, No. 5, pp. 582–584, May, 1996