A comparative study of corneal epithelial cell surfaces utilizing the scanning electron microscope.

Abstract

The mammalian corneal epithelium has been previously shown to have microprojections (microvilli, microplicae) which have been implicated in tear film retention in addition to other possible functions. In the present work, a comparative study of the corneal surface in several species of fish has been carried out with the scanning electron microscope in order to further probe the functional importance of these surface structures. The corneal microprojections in two elasmobranch species, the dogfish and skate (which have eyelids), are structurally very similar to one another, and resemble mammalian corneal surface microprojections. The five species of marine teleost (which do not have eyelids), on the other hand, show epithelial surface patterns consisting of long, curved surface ridges. Evidence of a material coating these ridges is presented. Individual cellular variations in surface coating material and structural patterns of the microprojections are reported. The possible roles of the corneal surface microprojections, in view of these comparative observations, are discussed. (auth)