Comparative anatomical study of oesophagus in two birds, Iraqi black partridge (Francolinus francolinus) and White breasted kingfisher (Halcyon smyrnensis )

Abstract

The oesophagus in both birds was long muscular tube, thin–walled and distensible tube, it was situated between the oropharynx cavity and proventriculus. The oesophagus in Iraq black partridge (Ibp) divided into three regions represented by anterior part (Cervical), median part (Crop) and posterior part (Thoracic),while in white breasted kingfisher (Wbk) its divided in two regions, anterior part (Cervical) and posterior part (Thoracic), because the crop was absent. In both birds, the anterior part (Cervical) of oesophagus located in the midline, dorsally to the larynx and trachea, which was fixed by connective tissue. In the median part of neck, the 0esophagus location changed where it was located on the right side of the midline, among trachea laterally and Jugular vein, vagus nerve and thymus dorsally. In (Wbk), the oesophagus was curved littleness on the right side of midline in contrast to the (Ibp). In (Ibp), immediately in the thoracic entrance, the oesophagus returns to the midline and it expanded ventrally pouch, (the crop) which was located between clavicle and breast muscles. The internal and external surface of the crop presented irregular folds. In (Ibp), the anterior part of oesophagus (Cervical) taken an (S) shaped because it was longer than its neck column. In both, the posterior part of esophagus (Thoracic) entered thoracic region and then located dorsally to the trachea, syrinx and heart, ventrally to the lung. Finally, the posterior part of oesophagus (Thoracic) opened in to the Proventriculus. In both birds, the anterior part of oesophagus (cervical) was longer than posterior part (Thoracic). The internal surface of the oesophagus demarcated with longitudinal folds.