ORIGIN OF THE SOMATIC-CELLS IN THE RAT GONAD - AUTORADIOGRAPHIC APPROACH

Gonads from rats of 11 and 12 days of gestation that had been given a pulse of 3H-thymidine were studied at different times using autoradiographic techniques. When the animals were labeled before the formation of the gonadal blastema (11 days), the percentage of labeled cells in this structure was greater than in the coelomic epithelium and mesenchyme. However, when 3H-thymidine was injected after the gonadal blastema was already established (12 days), very few of these cells took up the compound; they remained in this condition until the sexual differentiation of the gonad. From this characteristic, which is an indication of the early differentiation of the blastemal cells, one may conclude that the seminiferous cords arise from this initial cellular line. On the other hand, there appears to be a contribution of coelomic epithelial cells during the formation of the sex cords in the ovary.