الملخص

Abstract The present study represent the comparison of morphology and structure of the non- sensory components of the eye of two species of fresh water teleoast fishes : Chalcalburnus mossulensis , which found near the water surface , and Noemacheilus angora, which found in the water bottom and between the rocks . The Scleral structure was similar in both species in that consist of cartilages and collagen fibers. There were also common similarity in corneal components of the two species which include stratified squamous epithelium , Bowman’s membrane , collagenous stroma , Descemet’s membrane and Endothelium . The thickness of central and peripheral cornea were varied in the same cornea as well as between the two species . In both species the annular ligament (a structure composed of several rows of tightly stalked polygonal cells) in the peripheral cornea was identified which located between the stroma and Descemet’s membrane , on other hand the morphology and thickness of the annular ligament varies in the both species . The lens morphology was spherical in both species but in the N.angora larger than C.mossulensis and the stain density varies in the central and peripheral parts in both species . The choroid components were similar in both species which include choroid tapetum lucidum , argentea , several layers of melanocytes which varies in number between the two species and in the same eye , and choroid gland near the optic nerve emergency . The dimensions of iris in the C. mossulensis more longer than that of N. angora . The iris composed retinal and choroidal component and some variations noticed between the two species. There were variations in the structure and morphology of optic disc of N.angora include several papillae while that of C. mossulensis one papillae . The number and package of optic nerve folds , as emerged from the retina , varied in the both species .