Adaptation of Eye of the Egyptian Agama "Trapelus Mutabilis" According to Its Activity Pattern

Abstract

The present study gives brief discussion about some structure of the eye of the Egyptian agama, Trapelus mutabilis, according to its diurnal activity. One of necessary components of the eye responsible for focusing the light on surface of the retina is the lens and cornea. The Egyptian agama possess spherical lens with a biconvex surface, consists of single layer of simple cuboidal epithelial cells anterior to the subcapsular cavity and capsulated by a thin cellular capsule. The cornea of the Egyptian agama is a transparent thin-walled curved structure that covers front of the eye. Histologically, cornea is formed of five layers: epithelium, bowman's layer, stroma, Descemet's membrane, and endothelium. The inner surface of eyeball is lining by retina, which contains some projections with small pits and a wide single fovea. Retinal layers represented by retinal pigmented layer, photoreceptor layer, cellular layers, and neural one. Photoreceptor layer of retina contains both single and double cones. The conus papillaris is a simple coneshaped projection, heavily pigmented, and originating on top of the optic nerve that protrudes from retina into the vitreous chamber. The surface of conus papillaris has more projections with pits. Histologically, conus papillaris consists of blood vessels and many black pigment granules. The present study concluded that the lens and the transparent cornea with its curved appearance, and the cone photoreceptors only of the eye retina reflecting their adaptation to the diurnal activity pattern of the Egyptian agama.