Embryological Studies on the Sex Chromatin in man: I. Incidence of the Sex Chromatin in Various Organs During Development

Abstract

In an investigation of the incidence of the sex chromatin of intermitotic nuclei in the various tissues (skin, stomach and muscle) of 37 human embryos (crown-rump length 7.9—318 mm) and the ventral abdominal skin of 20 patients (10—80 years old), the following results were established. 1. In the early stages of 7.9—35.6 mm crown-rump length (4—9 weeks), the sex can not be determined from the form of external genitals, without error, but it is possible to distinguish it from the incidence of the sex chromatin of intermitotic nuclei. In the female embryos, the sex chromatin was identified in a comparatively high percentage of nuclei, and there are no marked differences of these percentages between the various tissues, as follows. In the epidermis of skin: adj. (adjacent to nuclear membrane) 55.9%, free (free from nuclear membrane) 35.4% : In the derma of skin: adj. 61.1%, free 18.6%. In the gastric epithelium: adj. 55.5%. In the gastric submucosa: adj. 57.1%. In the striated muscle (premuscular cell): adj. 65.3%. In the cardiac muscle (premuscular cell): 60.0%. In the smooth muscle (premuscular cell): adj. 64.8%. In the male embryos, the sex chromatin was identified in a comparatively low percentage of nuclei in each case, averaging 2.8% (0—7.6%). © 1964, International Society of Histology and Cytology. All rights reserved.