Specular microscopy of vertebrate corneal endothelium: a comparative study

Central corneal endothelia in a variety of lower- and higher vertebrate animals were photographed with a widefield specular microscope and analysed with either fixed-frame or computer-assisted morphometric analysis. The endothelium of the dogfish shark, an elasmobranch, contained 2300 cells mm-2 and demonstrated a very delicate irregular 'reversal pattern'. The goldfish, a teleost, had 432 cells mm-2 and displayed a jigsaw-puzzle-like pattern. The bullfrog, an amphibian, and the gecko, a reptile, had 550- and 481 cells mm-2, respectively, and a relatively uniform polygonal endothelial pattern similar to that observed in mammals. The goose, a bird, had a cell density of 2410 cells mm-2 with a uniform hexagonal pattern (79%) which was similar to mammalian (rat, 58-76%; rabbit, 71%; dog, 78%; human, 61-75%) hexagonal patterns. The findings on the endothelial appearance in these vertebrate animals suggest that a correlation exists between endothelial morphology, vertebrate phylogeny and their respective functional and structural capacity.