Control of epithelial development.

Interactions between epidermal and dermal cells of integumental systems exert finely regulated controls over epithelial development. Experimental reconstruction of skin tissues, in vitro and in vivo, from selected populations of dissociated embryonic chick and mouse cells provides a unique opportunity for analyzing the morphogenetic information intrinsic to individual cells. Dermal cells are shown not only to induce and specify particular epithelial structures; they also exercise the power to suppress potential developmental programs. Epidermal cells not only recognize and respond to dermal directives; they are also critical agents in the communication of cues for histogenetic patterning to both neighboring epithelial cells and subadjacent dermal elements. The role of the cell surface as a site for developmental control is discussed in the context of current evidence.