Observations on living oogonia and oocytes from human embryonic and fetal ovaries

Abstract

This report summarizes a series of observations on human oogonia and oocytes recovered from 22 living human embryos and fetuses with crown-rump lengths of from 22 to 171mm. Fragments from each gonad were examined immediately in specially prepared squash preparations. The remaining gonadal tissues were placed in tissue culture preparations and studied for approximately 80 days. Living human germ cells have the capacity for ameboid movement if examined before they are encompassed by follicular cells. Oogonia arranged in cords or clones have been observed to undergo repeated cell divisions in synchrony. After a number of cell divisions the oogonia stop dividing and enter the prophase of meiosis proceeding to the dictyotene stage. Some of the oocytes in tissue culture grow to diameters of 60 to 80 μ and develop incomplete secondary membranes. Multinucleate oocytes are seen frequently in the younger cultures. Most of them disappear by the fiftieth day in culture. Atresia is a common feature in oocytes growing in tissue culture.