Histological and developmental study of Choroid and Retina in Canadian ostrich embryo (Struthio camelus)

For this study, 12 healthy fertile ostrich eggs at ages of 22, 26, 30 and 36 days of embryonic stage and three one-day chicks were used. For histological study of different layers of choroid and retina, eye sections were stained with Hematoxylin-Eosin and Masson’s trichrome. The results showed that the three main layers of the eye on embryonic day 22 (fibrous, vascular and nervous) were formed. Connective tissue stroma of the choroid was seen with high matrix and collagen fibers on day 22 and they were not well defined and as distinct layers. Retina at the age of 22 days was composed of three main layers; the outer granular, inner granular and optic nerve fibers. At this age, the border between the inner and outer reticular layers were not well defined. At 26 days old, the size of the fibers in the stroma increased more specifically. Further development of the retina happened at 26 days old, and its constituent layers were separated and well defined. At the age of 30 days, choroid stroma contained collagen fibers and dilated blood vessels and the formed layers of retina were well developed. At 36 days old, the layers of the sclera, choroid and retina had reached maximum development. Choroid layer consisted of a relatively expanded area and contained dilated blood vessels, thin collagen fibers and abundant melanocytes. Histologically the chick eye components were not much different from those at embryonic day 36.