Abstract





The current study was carried out on thirty one camel embryos and fetuses with crown vertebral rump lengths (CVRL) ranging between (15-100) mm in order to follow-up the prenatal developmental stages of the nasal cavity. The microscopic examination of the obtained speci- mens revealed that the camel nasal cavity began as deep invaginations (nasal pits) which appeared in the rostral portion of the embryonic head. These invaginated pits be- came deeper and enlarged forming the primitive nasal cavities, which were separated from the primitive oral cavity by the oronasal mem- brane. This membrane then broken down and allowed both cavities to communicate with each other by the primitive choanae. Two shelf-like outgrowths grew ventrally from the maxillary prominences to eventually form the secondary palate. These shelves were initially directed obliquely and ventrally inside the stomodeum in a vertical direction on each side of the developing tongue. Rostral to the developing nasal sep- tum, a ventral evagination of the lining ectoderm was noticed on both sides of the nasal septum forming the epithelial lining of the vomoronasal organ meanwhile the surrounding mesen- chyme developed to be a curved plate of its hyaline cartilage. Two projections were noticed on the lat- eral wall of each nasal cavity to form the dorsal and ventral conchae. The ectodermal lining of the dorsal and lateral aspects of the nasal cavities differentiated into thick olfactory epi- thelium while that of the ventral and medial aspects became thin respira- tory epithelial coat. Based on the above-mentioned findings, it is no- ticed that the development of the nasal cavity in one-humped camel was histologically in succession.