Correlation of early cytodifferentiation of the human fetal prostate and Leydig cells.

The ultrastructural differentiation of the human prostatic epithelium and mesenchyme was studied in early developing glands and correlated with the differentiation of the Leydig cells of the same individuals during the tenth to sixteenth weeks. After initial folding of the basal lamina, the epithelial cells began to migrate into the differentiated, condensed mesenchyme at the end of the 10th week, and in the 11th week some of the prostatic outgrowths acquired a lumen. The acinar and tubular epithelium in the fetal prostate remained stratified, and adult type simple epithelium was not seen during the period between the 10th and 16th weeks. As a sign of incipient secretory activity, a few epithelial cells became polarized, and secretion granules with flocculent or dense content appeared in the Golgi area and in the apical parts of the cells in the 13th week. Occasional direct epithelio-mesenchymal cell contacts were visible in association with the appearance of the secretory activity. Two cell types, not seen in the normal adult prostate, appeared in the epithelium of the primitive glands. Their nature and role in the glandular morphogenesis are not clear. During this time, the ultrastructural differentiation of the Leydig cells continued and their size and number increased. They occupied almost the whole interstitium by the time secretion granules appeared in the prostatic cells. These findings support the current notion that androgens secreted by Leydig cells are the major regulators of prostatic development in man.