[Development of germ cells in the ovaries of human fetuses in the early periods].
Histological methods were used for studying 30 ovaries of early human embryos from 7 to 11 weeks of development. It was shown that in the process of development of the ovary the number of mitotically dividing oogonia decreased from 76% in 7-8 weeks to 41% in the period of 10-11 weeks. The mototic division of oogonia was characterized by high activity from 3,6% to 6,8%. However, as early as in the ovaries of 7-8 week embryos there occurred transition of a part of oogonia into oocytes of preleptotene stages which were characterized by processes of spiralization and despiralization of chromatin in the nuclei. The amount of such oocytes increases in the process of development of the embryo. The amount of oocytes at the stage of condensation of chromatin "prochromosomes" increases from 7,6% to 14,4%, the amount of oocytes at the stage of the following despiralization increased from 2,1% to 21% when comparing the ovaries of embryos of 7-8 and 10=11 weeks of development. The size of nucleoli was found to change in the period of preleptotene transformations in the oocyte nuclei. Photographs of the stages in question are presented made from histological and total preparations.
D002466:Cell Nucleolus; D002467:Cell Nucleus; D002843:Chromatin; D005260:Female; D005854:Germ Cells / Q000648:ultrastructure*; D005865:Gestational Age; D006801:Humans; D008938:Mitosis; D010053:Ovary / Q000196:embryology*; D010063:Ovum / Q000648:ultrastructure; D011247:Pregnancy
D002843:Chromatin
Razvitie germinativnykh kletok v iaichnikakh plodov checloveka rannikh srokov