Gross and microscopic anatomical study of the esophagus in Gasgie ecotype chickens in the Alefa District, Northwest Ethiopia

The Gasgie chicken is an important indigenous ecotype of Ethiopia that has adapted to diverse agroecological conditions and contributes substantially to the livelihoods of rural communities. However, despite its significance, comprehensive information on its anatomical features remains limited, particularly regarding the esophagus, which plays a vital role in feeding adaptation and digestion. This study aimed to investigate the gross and microscopic anatomy of the esophagus in Gasgie ecotype chickens from the Alefa District, Northwest Ethiopia. An exploratory experimental study was conducted at the University of Gondar from February to September 2025. Ten healthy chickens were purposively selected from the Alefa market and acclimatized for two weeks. They were humanely euthanized using 100% carbon dioxide (CO₂) inhalation, and the cervical, crop, and thoracic esophagus were examined grossly, microscopically, and morphometrically. Gross characterization revealed that the esophagus is a long muscular tube divided into cervical, crop, and thoracic regions, showing age- and sex-related differences in regional prominence, especially in one-year-old males. Gross morphometry demonstrated significantly greater esophageal dimensions in older and male chickens compared with younger and female counterparts (P < 0.05). Microscopic characterization showed that the esophageal wall consisted of tunica mucosa, submucosa, muscularis, and adventitia/serosa, lined by non-keratinized stratified squamous epithelium with mucus-secreting glands, and showed more complex mucosal folds in older chickens. Histomorphometric analysis revealed significant age- and sex-related differences in Gasgie chicken esophagus, with one-year-old and male chickens exhibiting consistently thicker epithelial and connective tissue layers across all regions (P < 0.05). This study provides baseline data for anatomical, physiological, and pathological reference. Further histochemical and ultrastructural studies are recommended, along with comparative analyses among ecotypes, and the findings should be integrated into veterinary anatomy curricula in Ethiopian universities.