Epithelial Desquamation in the Adult-Mouse Cornea A Correlative TEM-SEM Study

Abstract

The central as well as peripheral corneal epithelium of normal young adult mice consisted of light (young), medium (mature) and dark (hypermature) cells based upon their brightness under the scanning beam. Multiple holes of either partial or full thickness were observed in these cells and were more common in medium and dark cells. Small as well as large mounds devoid of microvilli also were found in medium and dark cells. TEM of the corneal epithelium revealed the presence of small and large cytoplasmic vesicles. Rupture of these vesicles and of the cell plasma membrane appeared to contribute to the formation of the epithelial holes. Full thickness holes within hypermature cells fused and thereby enlarged in diameter until the cell was replaced by an underlying new one. Furthermore, in TEM preparations, hypermature cells lost basal and lateral desmosomes and lifted off from the corneal surface.