Origin of cells in human oral mucosa heterotransplants in nude mice.

Species identification of cells was performed in a model to study epithelial-mesenchymal interactions using combinations of human and murine tissue. The study comprised 34 successfully recovered transplants of human palatal mucosa with 15 human epithelial outgrowths formed on uncertainly species-identified connective tissue. Formalin-fixed and paraffin-embedded 5-micron sections were stained with bisbenzimide (0.8 microgram/ml) and examined in an epifluorescence microscope. The nuclear-staining pattern revealed limited peripheral invasion of the transplanted connective tissue by murine fibroblasts. In areas of epithelial outgrowth a small number of fibroblasts could not be identified but most subepithelial fibroblasts were murine. The study supports previous findings which indicate that the altered differentiation of the human epithelial outgrowths was caused by the murine connective tissue underlying the human epithelium.