Wound repair of the oral mucosa. Immunohistological and 3H-thymidine-autoradiographic observations.

ABSTRACT

The migratory and proliferative capacity of oral epithelium was studied after induction of subepithelial suction blisters in palatal rat mucosa. FITC-coupled lectins and their affinities to epithelial cells at the wound margin were analyzed by immunofluorescence microscopy. Immunocytochemical distribution of 67 K-keratin polypeptides in different epithelial layers were studied using specific antisera against keratin proteins. By means of 3H-thymidine-autoradiography the proliferation of epithelial basal cells and their migration at the wound edge was quantified by evaluation of the labelling index. Double labelling was performed, combining the autoradiographic and the keratin staining technique. It was found that the subepithelial suction blister showed rapid repair (epithelial regeneration after 3-4 days). Peanut Agglutinin (PNA) showed a selective affinity to the basal 2-3 layers of oral rat mucosa. No modifications of lectin affinities were found in epithelial wound repair. PNA-positive keratinocytes were demonstrated in the migratory epithelial tongue. The selective presence of 67 K-keratin (67 K) in the suprabasal epithelial cell layers was interpreted as an indication of the differentiation process in rat oral mucosa. The 3H-thymidine-labelling index of basal cells increased significantly, beginning at the wound edge after 24 h. The peak of the labelling index curve was located in the vicinity of the wound after 96 h. Double labelling technique revealed 67 K-negative and 3H-thymidine-positive basal cells as well as 67 K-positive and 3H-thymidine-negative cells at the migration front. These observations support findings that migrating epithelial cells in oral wound healing derive both from undifferentiated (str. basale) and from differentiated (inferior str. spinosum) cell compartments.