Morphological and Histological Characteristics of Trachea in Iraqi Pin-tailed Sandgrouse

Abstract

This research explored the physical form of the Iraqi sandgrouse, as well as the internal structure of its trachea histologically. To achieve this, five (5) male adult sandgrouse from Al-Ghazel market, Baghdad, were used. Appropriate approval was obtained to perform this research on animals. The birds were anesthetized with chloroform and euthanized before being dissected. The trachea was taken from each bird, and cleaned with 0.9% NaCl, for use in the morphology of the cartilaginous rings and in histology studies. The present findings indicate that the trachea is a flexible tube made of cartilage and measures approximately 4.5 ± 0.167 in length extending from the end of the cricoid cartilage to the thoracic cavity, where it separates into two primary bronchi behind the base of the heart. The trachea has two sections: one proximal section attaching to the larynx with a diameter of approximately 0.57 ± 0.057 and a distal section connecting to the vocal organ (syrinx) with a diameter of approximately 0.57 ± 0.057. Histologically, the trachea is composed of three layers of tissue: mucosa, submucosa, and adventitia. Longitudinal striated muscle fibers that are multinucleated were visible supporting the adventitia. The mucosa is comprised of pseudostratified epithelium, while the submucosal layer is composed of loose connective tissue, and hyaline cartilage. The adventitia contains loose connective tissue and blood vessels. On histometric analysis, layer measurements revealed the mean thickness of the mucosa to be approximately 30.2 ± 1.6 µm, that of the submucosa to be approximately 205.8 ± 7.8 µm, while that of the adventitia was approximately 65.5 ± 6.4 µm.