Oval lipid corneal opacities in beagles: ultrastructure of normal beagle cornea

The ultrastructure of normal Beagle cornea was similar to the human cornea, except the Beagle lacked an anterior limiting lamina (Bowman's layer) and banding in the anterior portion of the posterior limiting lamina (Descemet's membrane). The epithelium was an average of 19 cells thick with 3 basic types: squamous, polygonal, and basal. The subepithelial stroma with a mean thickness of 9 microns was hypocellular, and the bundles of collagen were randomly oriented. The majority of the stroma consisted of closely packed, parallel collagen lamellae interspersed with keratocytes and occasional nerve fibers. The posterior limiting lamina was homogeneous and thick with increasing age. The endothelial cells formed a monolayer and had apical tight junctions.