Ultrastructural characterizations of the pecten oculi of the common ostrich (Struthio camelus): New insight to scanning electron microscope-energy dispersive X-ray analysis.

The current observation was designed to give a complete ultrastructural description of the pecten oculi of the common ostrich (Struthio camelus). Moreover, this study represents the first attempt to measurements the elements composition of the pecten oculi using scanning electron microscope-energy dispersive X-ray (SEM-EDX) at three regions (apical, body, and basal). To accomplish this study, eight ostrich were examined grossly and under the electron microscope. The vaned-shaped pecten oculi consisted of three regions (apex, body, and base) with 24-25 plates. The pecten oculi was located postero-anteriorly near to the optic nerve disc that was attached by their bases to the retina forming a slightly elevated basal border joining the bases of all pleats, while the apex was linked in a circular bridge. The pleats are separated from each other by the inter-pleat spaces that are very clear at the base and nearly not observed at the apical part. The outer pleat's surface carried numerous prominences that pointed to the existence of numerous afferent and efferent pecteneal blood capillaries vessels. The vitreopecteneal limiting membrane separated the pecten oculi from the vitreous body. Our findings concluded that, the high number of thick pecteneal pleats was related to the diurnal activity of the common ostrich. SEM-EDX shows that the carbon percentage in the three regions is the highest that representing about half of all elements, while the oxygen percent is about one-third; meanwhile, the lowest percentage is the sulfate at the apical region, and the calcium at the body and basal regions.