Mesenchymal-epithelial interactions in sex differentiation.

Development of male and female accessory sexual glands is described in terms of the respective roles of epithelium and mesenchyme. During embryonic and neonatal periods mesenchyme alone exhibits androgen receptor activity (nuclear androgen binding sites) and is the actual target and mediator of the morphogenetic effects of androgens upon the epithelium. Mesenchyme induces specific patterns of epithelial morphogenesis, cytodifferentiation, and probably also specifies the functional (biochemical) activities of the epithelium. Mesenchymal influence upon expression of epithelial characteristics occurs in the perinatal period during morphogenesis, but also plays an important role in adulthood by maintaining favorable conditions for maintenance of epithelial morphology and function. Morphogenetic processes in adult hormone-dependent organs are though to be mediated by stromal cells.