Connective tissue influences on patterns of epithelial architecture and keratinization in skin and oral mucosa of the adult mouse.

Epithelial-mesenchymal interactions play an important role during embryogenesis but it is uncertain whether such interactions influence the maintenance of epithelial structure in the adult. To examine this problem, separated epithelial and connective tissue components of skin and mucosae from various regions of adult mice were homo-or heterotypically recombined and transplanted to histo-compatible hosts. The patterns of tissue architecture and keratinization of the resultant epithelia were examined for changes indicative of mesenchymal influences on the epithelial phenotype. Each type of epithelium, in some recombinations, fully conserved its normal pattern of phenotypic expression indicating that subepithelial connective tissue from all regions is permissive and that regionally-specific connective tissue influences are not necessary for conservation of epithelial specificity. In other recombinations, however, the epithelium acquired features of tissue architecture or keratinization typical of the epithelium normally associated with the connective tissue component, indicating directive influences from the connective tissue. The patterns of epithelial response observed suggest that there may be separate connective tissue influences on epithelial architecture and cyto-differentiation and that there is a regionally-related variation in the competence of epithelia to respond to these influences.