Abstract
Purpose: :
To investigate by autoradiography the regenerative capability of the epithelium of the central region of the rabbit cornea following 7 consecutive scrapings of the epithelium of the peripheral cornea.
Methods: :
Three pairs of male adult albino rabbits where studied. After marking the center of the cornea with a 6 mm-diameter trephine, the epithelium outside this area was scraped until reaching the corneoscleral zone. The procedure was repeated 7 times on the same eye at intervals of 20 days. After the last scraping, 3H-thymidine was injected intravitreally and the corneas processed for autoradiography.
Results: :
At 3 days after injection the cornea surface was lined completely by an epithelium made up by two layers of squamous cells, most of them labeled with the DNA precursor. A multilayered epithelium was visualized at the center with most of its basal cells also labeled. The limbal epithelium had at least two layers labeled with the precursor. At 9 days the multilayered central epithelium exhibited labeled cells not only in the basal but also in the suprabasal layers. The labeling index (labeled nuclei/100 cells) for the basal stractum was very close to 100%. A similar feature was observed at 16 days except that the multilayered epithelium increased in area, from the center to the periphery, when compared to the precedent interval and that it exhibited evidences for vertical renewal.
Conclusions: :
The epithelium lining the central region of the cornea - where it is assumed the inexistence of stem cells - exhibited capability for regeneration and reconstitution ad integro in spite of 7 consecutive debridements of its periphery. The proliferation observed in the limbal epithelium did not interfere with the events taking place at the center of the cornea.
Keywords: cornea: epithelium • cornea: basic science • proliferation