Ultrastructural study of the posterior cornea of the dogfish "Scyliorhinus canicula L".

The cornea of Elasmobranchs remains transparent and exhibits a remarkable resistance against swelling when deprived of its endothelium. Sutural fibers, which traverse the corneal stroma anteroposteriorly, may be responsible for this property. We studied the structure of the cornea of Scyliorhinus canicula L., a galeiform Elasmobranch, with special emphasis on the presence of a corneal endothelium and on its appearance during development. Observations were made with the aid of several microscopic techniques: light and specular microscopy, transmission and scanning electron microscopy. We found that the posterior corneal surface was always covered by a fibrillar material. A structural counterpart of endothelial-like cells on the posterior cornea or in the anterior chamber was never observed in adult fishes and in embryos of different stages. In contrast, in Torpedo ocellata, a torpediniform Elasmobranch, endothelial cells were seen. The significance of these findings is discussed in context with the possibility of technical artefacts and compared with other studies.