Abstract
Regeneration of the rat tracheal epithelium following mechanical injury was studied by electron microscopy and immunohistochemistry. The first event that occurred following the injury was rapid flattening of the viable epithelial cells of the wound margin and their migration to the injured area. In the early stage, the regenerating epithelium changed from a simple squamous to a multilayered structure, or typical squamous metaplasia.
Immunohistochemically, keratin was detected in the regenerating cells, and actin was present linearly along the basal cell membrane of the migrating epithelial cells. Fibronectin also appeared in the wounded stroma immediately beneath the migrating epithelium until the migration was completed. Both laminin and type IV collagen reappeared under the regenerating epithelium from the wound margin after the migration was completed in the middle stage.
Ultrastructurally, fibronexus-like structures and so-called anchoring filmaments appeared in the epitheliumstroma junction before hemidesmosomes, basal lamina and anchoring fibrils reappeared. We consider that both fibronexus-like structures and anchoring filaments are responsible for the initial adhesion of the regenerating epithelium to the underlying connective tissue.
