The influence of gonadic hormones on skull differences in rats malnourished during lactation.

ABSTRACT

One hundred and twenty five Holtzman rats of both sexes were submitted to malnutrition during suckling with or without periodic injections of testosterone enantate in males and estradiol valerianate in females. Ten cranial measurements were made, and morphological differences within and between sexes were calculated by multivariate Mahalanobis D2-distances. Malnutrition delayed the cranial difference between sexes, which was restored by hormonal treatment. Testosterone arrested the skull size difference between sham and malnourished males. Estradiol stimulated the skull size difference between sham and malnourished females. This counteracting effect indicates that at early ages, both hormones stimulate sexual cranial dimorphism when a protein-calorie malnutrition acts on both sexes.