This study examined the histological features and histochemical properties of the gizzard in pigeons. The lateral wall of the gizzard displayed all four tunics, with an additional thick layer of koilin towards the luminal surface. The mucosa exhibited folds, followed by gastric pits formed by gastric glands. The lamina propria merged with the submucosa, lacking a distinct lamina muscularis. The tunica muscularis consisted of inner circular, middle oblique, and outer longitudinal layers of smooth muscle fibers. The tunica serosa formed the outermost layer. These findings were consistent with previous studies in broilers and Elanus caeruleus, but differed from observations in mallards and laughing doves. The central wall of the gizzard displayed koilin, a mucosa with folds, and gastric pits lined with cuboidal epithelium. The propria-submucosa exhibited dense connective tissue fibers, and hyaline cartilage was present in the middle portion. The tunica muscularis was absent, and the tunica serosa consisted of connective tissue fibers and mesothelial cells. Micrometry measurements revealed the thickness of various layers in the gizzard. Histochemical analysis showed the presence of neutral mucopolysaccharides and acidic mucosubstances in the epithelium, tunica muscularis, lamina propria-submucosa, and tunica serosa. Elastic fibers were observed in blood vessels, and collagen fiber bundles were interspersed within the tunica muscularis.
In summary, this study provides a comprehensive histological and histochemical characterization of the pigeon gizzard, highlighting the unique features of the lateral and central walls. These findings contribute to our understanding of avian digestive physiology and offer a basis for comparative anatomical studies.