Mesenchymal-epithelial interactions in hormone-induced development.

An hypothesis of hormone action upon epithelial growth, morphogenesis and cytodifferentiation is proposed in which certain hormonal effects upon epithelial cells are postulated to be mediated by nonsteroidal growth factors or morphogens elaborated by hormone-sensitive mesenchymal cells. Through this process mesenchymal cells induce specific patterns of epithelial morphogenesis and functional (biochemical) activity within urogenital epithelium.