The healing of corneal epithelial abrasions in the rabbit: a scanning electron microscope study.

The morphologic appearance and time course of regenerating rabbit corneal epithelium was studied after 6.0 mm. corneal abrasions. The immediate response to injury was separation and thickening of basal and squamous epithelial cells at and near the wound margin. A variable number and distribution of polymorphonuclear leukocytes appeared on the basal lamina and regenerating epithelial edge at 3 hours, persisting up to 38 hours after abrasion. Most of the epithelial cells at the wound margin were extensively flattened after 15 hours. These flattened epithelial cells showed a wide variety of surface ruffling near their free edges. This ruffling activity often was associated with long fingerlike processes (filopodia) extending out on to the basal lamina. The method of epithelial cell movement on the basal lamina appeared to depend mainly on the ruffling and filopodial activity of squamous epithelial cells. Ruffles and filopodia projected out ahead of the cell edge, contacted the basal lamina, and appeared capable of drawing the cells forward into the area of the defect. Normal corneal re-epithelization proceeded with two or three cell layers moving as an orderly sheet over the basal lamina until the defect was closed. The corneal surface showed no defect at 55 hours and was returned to normal at 114 hours.