Morphometric analysis of the surface cells of rabbit corneal epithelium by scanning electron microscopy

The corneal surface of female New Zealand white rabbits (1.9-2.6 kg) was examined at x500 magnification by scanning electron microscopy. A total of 112 micrographs, taken as sequential sets from the center to the edge of the corneal surface from 8 different animals, was analyzed using a digitizer pad. Each cell was identified by the number of immediately bordering cells and by the nature of its electron reflex (light, medium, dark). Analysis of areas of the cells by number of bordering cells (number of cell sides) reveals a wide range of areas and skewed distributions especially when the number of sides is 5 or less. Overall, the cell-surface area increases as the number of cell sides increases. However, analyses of the mean surface areas for cells with different numbers of sides and additionally grouped by electron reflex suggests the existence of three separate populations of cells at the corneal surface. The possible etiology and dynamics of this complex cell mosaic are discussed in relation to circadian rhythms and to resurfacing of the cornea following mechanical trauma, ultraviolet radiation, and toxic chemical exposure.