This study was carried out to investigate the anatomical and histological structure of larynx, trachea and syrinx in male and female chickens of Aseel breed. Healthy adult chickens of Aseel breed, including 4 female and 4 males were used in this study. By dissecting the neck and chest cavity of the birds, topographical characteristics of larynx, trachea and syrinx were recorded. The dissected tissues were microscopically examined by staining with hematoxylin and eosin by using routine histological procedures. In this breed, larynx was composed of cricoid cartilage, procricoide cartilage and a pair of arytenoid cartilage while thrachea contained 111-118 cartilage rings. Surfaces of transversal sections of cartilage rings changed along the trachea. A series of papillae caudally directed and sequentially located along the lateral borders of glottis were observed. At the back side of laryngeal sulcus, two series of transversally located papills with backward directed free ends were detected. Syrinx was observed in the tracheobronchial type. Tympanum was observed to be composed of four cartilage rings. By microscopic examination of larynx mucosa was observed to be covered by multilayer keratinized epithelial tissue. The mucous glands and hyaline cartilages were present in the lamina propria. Tunica mucosa of syrinx was covered by pseudo multilayer ciliar epithelial cells. The pessulus was composed of hyaline cartilage.

The results indicated that although differences in trachea lentgh and diameters of cartilage rings existed between sexes, larynx, trachea and syrinx in Aseel breed were highly similar to those in other chicken breeds.