The proliferative response during regeneration of a ringshaped defect in the corneal epithelium

The aim of the present study was to investigate the regenerative ability of the central corneal epithelium in an in vivo situation, as previous studies have been contradictory regarding the proliferative potential of these cells. Paracentral ringshaped defects were made in rat corneal epithelium, using filter paper soaked in n-heptanol. Cell counts, labelling indices and mitotic rates were measured in sections from the corneal and the adjacent conjunctival epithelium 12 and 28 h after the injury. The cell counts indicated that also central corneal epithelial cells migrate in the early phase of wound healing. No proliferative response was seen in the central corneal epithelium after 12 h. At 28 h both the peripheral and central corneal cells showed an enhanced labelling index, while the mitotic rate only was increased in the periphery. Different cell cycle times and different levels of differentiation of the cell population across the cornea may explain the delayed proliferative response in the central cornea.