The Epithelium in Corneal Wound Healing

Tritiated proline was administered to eyes with perforating corneal incisions 5–9 days after the incision to evaluate the biosynthesis of collagen under different experimental conditions. The radioactivity of the corneal tissue was counted after an exposure of 5 h to the isotope. There was significantly less proline uptakein the wounded corneas in which the epithelium was scraped and kept away after wounding either with adhesive barriers or glued-on lenses, as compared to wounds with the epithelium left undisturbed. No decrease of proline incorporation occurred when the scraped epithelium was allowed to grow back, indicating that the trauma of scraping per se was not responsible for the abolishment of the proline uptake. Scraping the epithelium after the exposure to proline led to a lesser decrease of the radioactivity, indicating that the epithelium participated actively in the biosynthesis of stromal collagen. The fact that the epithelium itself was heavily labeled with isotope strengthens the hypothesis of the epithelium being directly involved in the production of collagen or its precursors.