Effect of Sexual Maturation and Castration on the Sex Chromatin Pattern in the Male Rat

Abstract

THE ‘nucleolar satellite’ described by Barr and Bertram¹ is generally considered to be of chromosomal origin and is, therefore, determined genetically. That is why, theoretically, the incidence of sex chromatin bodies is not influenced by age, or exogenous and endogenous factors. Davidson and Smith², recognizing the sexual dimorphism of leukocytes, thought that the ‘drumstick’-form, which is characteristic of females, represented a fusion of the heterochromatic segments of two paired X chromosomes. However, certain signs would seem to indicate that the chromatin condensations in leukocytes do not show, in every respect, the properties of the ‘nucleolar satellites’. In addition to the female ‘drumstick’, several authors^3,4 have observed so-called pseudo-forms, the occurrence of which is also related to actual sex. At the same time it cannot be unambiguously explained how it is possible that chromosome pairs have so many, variegated and yet nonspecific morphological equivalents. The foregoing facts and the presumptive relationship between sexual hormones and leukocytes has tempted us to study in leukocytes the hormonal relations of the sex chromatins, especially those of the pseudo-forms.