[Morphologic and quantimetric study of the surface of the corneal epithelium]

Studies were conducted to attempt to demonstrate the presence of a twofold cell population in the superficial cells of the corneal epithelium as seen on scanning electron microscopy. Transmission electron microscopy was used to compare corneas washed with acetylcysteine with unwashed corneas after staining of surface mucosubstances with ruthenium red. Washing was found to remove some of the mucus film deposited by the tears on the epithelial surface. In contrast, both specimens showed a layer of substance, stained by the ruthenium red and more or less abundant according to the cell, which was thick enough to mask the microvillosities on scanning microscopy. Two distinct layers were observed. One of constant thickness was a thin layer which followed the outline of the microvillosities exactly but did not mask them. This was formed of glycocalix itself, a substance of cellular origin which was visible on developed cell surfaces even before desquamation of adjacent cells occurred. The other layer was more heterogeneous and attached to the cell wall, but it cannot be removed by washing with acetylcysteine. It also appeared on developed cell surfaces before adjacent cells had desquamated. The substance could arise from the lacrimal film or the necrozed remnants of superficial cells. It appears to increase in quantity with aging of the cell, and is capable of infiltrating between the microvillosities giving the appearance of dark cells on scanning microscopy. The different cells noted on scanning microscopy vary only by the amount of this mucin-like substance.(ABSTRACT TRUNCATED AT 250 WORDS)