Fetal Differentiation of the Lower Respiratory Tract of the One Humped Camel (Camelus Dromedarius): Gross Observation

A study involving gross differentiation was conducted on the lower respiratory tract of 52 foetuses of the one-humped camel collected from the Sokoto metropolitan abattoir, over a period of five months at different gestational ages. Sex differences were not taken into consideration. The approximate age of the fetuses was estimated from the crown vertebral rump length (CVRL) and samples were categorised into first, second and third trimester. Observation of the trachea reveals the division in to cervical and thoracic part in all the stages of development (early, middle and late). At first trimester, the cervical trachea is located along the ventral midline of the cervical region with the esophagus lying dorsal and to the left. The cervical part of trachea was observed to have been covered ventrally by the right and left sternohyoideus muscles and laterally by the sternothyroideus muscles in all the stages of development. The trachea continues to increase in size, shape and diameter resembling adult camel from the early third trimester of age. The tracheal cartilages were observed to appear at the late first trimester. They are c-shaped and incomplete dorsally with the ends of the tracheal cartilages joined by smooth muscle (musculus trachealis) in all the stages of development. The tracheal rings ends meeting of the right end with the left end between the trachealis muscles, the carotid sheath is dorsolateral to the trachea from early second trimester to late third trimester of age.