Cell junctions in squamous epithelium during wound healing in palatal mucosa of guinea pigs.

The nature and distribution of cell junctions of the epithelium of wounded guinea pig palate were studied. Biopsies, 32 in total, were taken 18, 48, 96, and 120 h after wounding. Desmosomes were present in the wound epithelium throughout the observation period. Primitive desmosomes, indicating de novo formation of desmosomes, were observed at the front of advanced migratory lips (48 h) and in the central region and the wound epithelium after bridging (96 and 120 h). Similarly, de novo formed hemidesmosomes were seen. They occurred along epithelial cell membranes exposed to the fibrinous wound exudate during the migratory lip stages (18 and 48 h) and after epithelial bridging. The observations suggest that wounding induced changes in the mechanical properties of the tissue. Gap junctions were present in migrating epithelium preferably at the stem of the lips and in the epithelium after bridging, which suggests their participation in regulation of the epithelial cell differentiation. Tight junctions, capable of acting as seals, were absent or fragmentary at best. A relative decrease in the volume density of intercellular spaces in migrating epithelium as compared to intact epithelium, suggests an in vivo tissue reaction.