Morphometrical and Histological study of esophagus in adult partridge (Alectoris chukar)and Harrier(Circus aeruginosus )

This study was conducted to identify the morphometrical and histological characteristics of esophagus in adult Partridge ( Alectoris chukar)and Harrier (Circus aeruginosus).To conduct such a project, twenty healthy adult partridge and Harriers, ten of each species were obtain from local hunters which was between 1 and 2 years old and weight about 400 to 550 gm. for Partridge and 2 to 3 years and the weight ranges from 390 to 750 gm. for Harrier. Birds were killed with an intramuscular injection of ketamine and diazepam, then dissected to collect esophageal specimens, which were cleaned with normal saline .The length and diameter of esophagus were measured, then specimens were stored in 10% formalin for 48 hours to underwent normal histological technique. Hematoxylin-eosin and Crossman's stain were used to stain sections. Gross findings of the esophagus revealed that the esophagus of Partridge and Harrier was a muscular, long and thin translucence tube divided into three parts include cervical, thoracic and abdominal parts .Histological structure of the esophagus wall in both consisted of three well-defined tunics. Tunica mucosa of partridge consists of stratified squamous epithelium which was significantly higher than the epithelium of Harrier and consists of high numbers of esophageal glands and lymphatic nodules compeer with that of the Harrier's esophagus, while the thickness of the muscular tunica of Harrier esophagus was thicker than that of partridge. The variation in the esophagus of the partridge and harrier was related to the food types consumed and feeding behaviors.