A histological study of the outer layer of rabbit fish (Siganus javus) eye

The rabbit fish is an economically valuable teleost species which lives in shallow coastal waters amongst aquatic plants. Two species of rabbit fish, Siganus sutore and Siganus javus, have been identified in the sea south of Iran. In this study, in order to investigate the histology of the outer layer of the S. javus eye, the eyes of 12 healthy specimens of S. javus were extracted and histologic sections were prepared. The sections were studied under a light microscope after staining with hematoxylin and eosin and Masson's trichrome stains. The outer layer was composed of the cornea cranially and the sclera caudally. The sclera contained an episclera zone and two cartilaginous segments with connective tissue correlation. The cornea included dermal components (stratified cuboidal epithelium, Bowman's membrane, and dermal stroma with occasional flattened cells); the scleral part consisted of two main layers (irregular fibers of connective tissue overlaying the second scleral stroma layer). The fibers of the scleral stroma were the only component present at the posterior part of the cornea. These results reveal that the eye of S. javus does not possess Descemet's membrane or endothelium in the cornea.