SEX CHROMATIN IN VARIOUS MAMMALS

Abstract

A morphological sex difference was observed in nuclei of nervous and non-nervous tissues of the timber wolf, black bear, red fox and coyote of the order Carnivora. The pig, a member of the order Artiodactyla, showed sexual dimorphism in neuronal nuclei only; multiple chromatin masses obscured any sex difference which may be present in other tissues. In the porcupine, a rodent, a nuclear sex difference was present in cells of the adrenal cortex and medulla, smooth, skeletal and cardiac muscle, and stellate ganglion, other tissues of this species did not show a nuclear sex difference. The mouse and prairie dog of the order Rodentia showed no sex difference in nuclear morphology in the tissues examined. Similar chromatin patterns were observed in nuclei of the male and female armadillo of the order Edentata; a practical sex difference was not present in this species. The sex characteristics of the interphase nucleus are discussed with reference to chromosome constitution, probable derivations of the sex chromatin, and the possible relationship of sex chromatin to cell metabolism.