Quantitative studies of corneal epithelial wound healing in rabbits.

Corneal epithelial defects are covered rapidly by the movement of adjacent epithelium. However, the mechanism of this tissue movement is poorly understood. In this study, the quantity or cell water, protein, and DNA were determined in healing epithelium to test the hypothesis that cell enlargement contributes to the rapid coverage of the defect. In addition, light and transmission electron microscopy and [3H] thymidine incorporation into epithelial cells were used to determine whether the healing tissue moves as a unit or as individual cells. The quantitative determinations lead us to conclude that healing begins with a dramatic rise in cell water, followed by an increase in cell protein and finally by a gradual increase in DNA. The morphologic and autoradiographic evidence strongly suggests that large corneal epithelial defects in rabbits are covered by the movement of adjacent tissue as a unified, multilayered sheet of cells. Furthermore, the cells appear large than normal with minimal changes in intercellular spaces. We suggest that the increase in cell volume is due to water uptake, which plays an important role in covering the defect by increasing the cells' surface area. Protein is then accumulated, followed by cell proliferation.