Susceptibility of epithelia to directive influences of mesenchymes during organogenesis: uncoupling of morphogenesis and cytodifferentiation.

Morphogenesis and functional cytodifferentiation are two major events in organogenesis, and normally they take place inseparably either in vivo or in vitro conditions. In this article, we reviewed a series of our recent results on mesenchymal-epithelial interactions in organogenesis of digestive organs, urogenital organs and the skin of avian and mammalian embryos, giving special attention to the importance of the responses of epithelia to the directive influences of mesoderms and also to the uncoupling of morphogenesis and cytodifferentiation, which has often been observed during the course of these studies.