Meckel's diverticulum in animals and birds: An immuno-pathoclinical perspective

Abstract

Background: Meckel’s diverticulum (MD), also known as vitelline diverticulum, is a congenital anomaly found in animals and birds as an appendage of the small intestine with immuno-pathoclinical significance. Methods: The author used PubMed and Medline search engines for articles containing terms such as Meckel's diverticulum, animals, birds, histopathology, complications and immune functions. From the abstracts of those articles, relevant articles were selected and reviewed them in detail. All the relevant major review articles and trials were included. The articles, which were available in full text English language, were selected. Additional articles were identified by a manual search of the references from the reviewed articles. Results: MD is a vestigial remnant of the omphalomesenteric duct. MD is most commonly found in horses and swine and less common in ruminants, carnivores and aves. The gross morphology and location on small intestine varies species to species. Hereditary, breed, age and sex are the factors that influence the occurrence of MD in animals. Histologically the wall of the diverticulum is of the same construction as the small intestinal wall (mucosa, submucosa, muscular and serosa coats) with a few exceptions like lack of villi and has a large amount of aggregated lymphoid follicles in its tunica mucosae, and also its muscularis mucosae. MD is a novel lymphoepithelial organ in the birds because of its high amount of lymphoid tissue. It produces large number of plasma cells which are comparable to those of the gland of Harder. MD is not generally of great clinical importance, but it is occasionally involved in several pathoclinical complications like recurrent colic from impaction, the development of peritoneal adhesions and strangulations in animals. Conclusion: The information included in the review regarding the development, prevalence, morphology, immunological and pathoclinical significance of Meckel’s diverticulum is supportive to prevent complications which will result in morbidity and mortality in animals and birds.