Anatomical and histological study of eye structure in the Iraqi Pin – tailed Sandgrouse bird Pterocles alchata caudarus

Ashgar Abed, Ali

	Anatomical and histological study of eye structure in the Iraqi Pin – tailed Sandgrouse bird Pterocles alchata caudarus
Tikrit Journal of Pure Science
Article 1, Volume 15, Issue 2, 2010, Pages 246-260
Author
Ali Ashgar Abed
Abstract
The present study include the anatomical features and histological structure of eye in the Iraqi Pin – tailed Sandgrouse bird Pterocles alchata caudarus. Ten birds eye were dissected and the results obtained were as follow:- The cornea of the eye composed of stratified squamous epithelium which settled on undulating Bowman's membrane . Alternative to the membrane was corneal stroma which composed of dermal and scleral regions. Beneth the stroma was Descement membrane which lining with single layer of endothelium. The specific results was the presence of pigment cells at the inferior border of the stroma at the base of the peripheral portion of the cornea . The scleral structure include cartilage and collagenous fibers. The choroids appeared as a high vascular layer which comprised blood capillaries and more larger vessels. All the vessels surrounded by arings of pigmented cells. The seldom structures in the birds which appeared in the choroid of Pin – tailed Sandgrouse were the lymphatic vessels and tapetum lucidum. On the other hand the Bruch's membrane, which separate the choroids and the retina, appeared folded. The folds of ciliary body was structurally distinct as two triangulars near the retina and at the base of iris . Two epithelial layers covered the fold surfaces, which were an inner pigmented and outer cleared one. The iris appeared convex anteriorly toward the cornea and appeared thin at the base, as well as, at free end. The anterior surface of the iris covered by pigmented epithelial cells. The lens appeared biconvex , smooth and translucent. There were two incisions at it's surface and had no annular pad. The retina of Pin – tailed Sandgrouse appeared duplex, and a vascular with one central fovea superior to the optic nerve. One area centrales also appeared as a strand upper to the fovea. The dorsal retina thickness more than that of ventral one. The pigment epithelium of the retina were columnar cells layer with central nuclei and folded basement membrane. The retina consist of one type of rods , three types of single cones and double cone. The cones density more than rods. On the other hand, Oil droplets appeared in the apex of ellipsoid in all cones types the other layers of the retina resembles that of other vertebrates except the thickness in the dorsal region more than the ventral region. The pectin oculi appeared as a sphenoid structure originated from the optic disc region as a transverse bridge . About twenty fold extended from the bridge which appeared as accordion system . The apex of the folds free without bridge. Histologicaly the pecten oculi composed of a dens network of capillaries with pericytes, blood vessels large and small and pigmented intervascular tissue. The pecten oculi protrude in the vitreous humour but not reach the lens.

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