ABSTRACT
Mesenchymal-epithelial interactions are known to be of utmost importance during development. In many developing organs mesenchyme regulates epithelial growth, induces specific patterns of ductal branching morphogenesis, specifies epithelial morphology and spatial organization, and elicits specific patterns of epithelial cytodifferentiation and functional activity. This chapter examines the role of mesenchymal-epithelial interactions during fetal and postnatal periods, including adulthood. Cell culture studies cast further doubt on the idea that estrogens act as direct mitogens on normal estrogen target epithelial cells. The male genital tract develops from two embryonic anlagen: the Wolffian ducts and urogenital sinus. The Wolffian duct, whose epithelium is mesodermal in origin, gives rise to the epididymis, ductus deferens, seminal vesicle, and ejaculatory ducts. In both the male and female genital tracts stromal cells appear to play key roles in regulating a variety of androgenic and estrogenic effects in epithelial cells.
