Abstract
The study applied light to investigate the microscopic and macroscopic results of the trachea and lungs in adult Iraqi pigeons (Columba livia). Age of the pigeons was (8-12) months. Our study was carried out 12 adult pigeons. These pigeons were supplement from local market of Baghdad city, Iraq. The morphological study of adult pigeon observed that the trachea included long tube of cartilaginous structure is extended from larynx until enters to left and right lungs with runs alongside the esophagus inside the thoracic cavity. This trachea was characterized by flexible bulk, non folded ring and numerous series of thin complete cartilage ring. The statistics analysis was used for grossly morphological organs, where was number of thin cartilage rings average range (67-70) complete rings. The study used the morphometric measurements for length of the trachea was (10±0.6) cm. and diameter of ring lumen about (0.6±0.12) cm.. Either the lungs results of adult pigeons were showed pink color, spongy mass and trapezium- like. The lungs were located inside thoracic cavity and connected by ribs with appearance costal impressions on the dorsal surface of the lungs. The morphometric study were included statistic analysis of lungs, weight of lungs were about (6±0.01) mg. and length was ( 3.32±0.2) cm. . Histological study showed tracheal ring of Columba livia was thin complete. The study observed histological layers included tunica mucosa, submucosa and adventitia, the first portion of mucosa is called epithelia, it’s characteristic by ciliated pseudostratified columnar epithelium with goblet cells, lamina properia has loose connective tissue which it is rich blood vessels. Submucosa is a beneath layer of mucosa, and contains tracheal cartilaginous tube, large blood vessels and numerous seromucous glands. Pigeon’s lungs were formed than parabronchi, it’s located in center of pulmonary lobule and separated by septa (connective tissue) named interlobular wall, which is originated from secondary bronchi and united with other. The epithelia lined the parabronchi by simple squeomous cells to help gaseous exchange inside the lungs .

Key words: trachea, lungs, pigeons, histology, morphometric