Morphological features of the distal ileum and ceca of the common pigeon (Columba livia)

Background to the study: Common pigeon ( Columba livia ) is widely distributed worldwide and feeds mainly on grains or seeds and insects and small invertebrates. Some studies have demonstrated variations in the morphology and function of avian alimentary tract. Methods: Ten apparently healthy adult common pigeons were examined in this study. Following euthanasia, gross and histological techniques were used to investigate the morphology of the distal ileum and ceca of common pigeon. Results: At the ileo-ceco-rectal junction, the tunica muscularis of the distal ileum exhibited a thickened layer of oblique smooth muscle fibers positioned between the middle circular and outer longitudinal smooth muscle layers. The ceca of the common pigeon were paired, small (approximately 0.33 cm), blind-ended sacs situated at acute angles with the distal ileum. Histologically, each cecum exhibited a lamina propria-submucosa that contained aggregates of lymphocytes and few glandular acini throughout the length of the organ. Conclusion: It was suggested that the ceca of the common pigeon may be important in immunological response of the bird to invasion by antigens while playing some roles in the digestion of food materials. Moreover, the thickened oblique layer of smooth muscle fibers in the wall of the distal ileum may serve to regulate the passage of materials through the ileo-ceco-rectal orifice. Keywords: Cecum, common pigeon, distal ileum, lamina propria‑submucosa, sphincter