[Change in the gonocytic nucleĭ at different stages of their differentiation in early human female embryos].

Fourteen human female embryos at the age of 18, 32, 33 days and 6, 7, 9, 10, 11 weeks fixed in Carnoy's fluid and in 12% neutral formalin have been studied. Paraffin sections stained with hematoxylin, methyl green - pyronine were examined under light microscope. Staining with fluorochrome Xexct 33258" was applied for luminescent microscopy. Gonocyte nuclei both localized in the wall of yolk sac and during their migration differ from somatic cells by "blasomere" type of their nucleus organization. During this stage of development, gonocyte nuclei have no sex chromatin, although it is distinctly detected in the nuclei of surrounding somatic cells in the same embryos. After the gonocytes had contacts with "germinal" epithelium, heterochromatization of one X-chromosome occurs. Sex chromatin is preserved in the nuclei of oogonia disappearing in the course of preleptotene. At differentiation in oogonia, the nucleus of sex chromatin and the structure of their chromatin undergo certain changes.