The influence of subepithelial connective tissues on epithelial proliferation in the adult mouse

Subepithelial connective tissue is capable of modulating the pattern of histodifferentiation of stratified epithelia from adult animals, but it is not known whether the supporting connective tissue also influences epithelial proliferative activity. Epithelial and connective tissues of murine skin and oral mucosa, differing in their morphology and proliferative activity, were separated and heterotypically recombined prior to grafting to histocompatible hosts. After 3 or 8 weeks in situ, mitotic activity was determined following the administration of vinblastine sulfate. Although the mitotic activity in each of the epithelia could be modulated by some connective tissues, there was no distinct pattern of behavior. In combination with connective tissues from tongue or palate, the ear epidermis acquired a significantly increased mitotic activity. In contrast, when oral epithelia with high mitotic activity were recombined with dermal connective tissue, there was usually a significant reduction in proliferative activity. As there was no apparent association between mitotic activity and the induced changes in either organization or histodifferentiation, it is suggested that subepithelial connective tissue is capable of directly influencing the mitotic activity in the overlying epithelium.