The junction zone of human epithelium and foreign stroma. Ultrastructural observations in human oral mucosal transplants in nude mice.

This study describes ultrastructural features of epithelial-stromal junction of human buccal and palatal mucosal transplants and their outgrowths in nude mice. The investigation included transplant epithelium overlying human connective tissue in 27 cases, epithelial outgrowth formed over murine connective tissue in 33 cases, and over Millipore filter in 12 cases. The epithelial-stromal junction of the transplants differed from the normal state only in the presence of lamina densa loops projecting into the connective tissue and in lamina densa interruptions and duplications. In contrast the epithelial outgrowths demonstrated flattening of epithelial basal cells, lack of proximal epithelial cell projections, lack of complete hemidesmosome complexes, lack of distinct lamina densa, and lack of anchoring fibrils. It is suggested that these changes may be due to lack of necessary interaction between the human epithelium and the foreign stroma.