Histology and ultrastructure of the palatine tonsils of the buffalo [Bos bubalus]

ABSTRACT

The palatine tonsils are the first lymphoid tissues along the digestive tract and play a key role in initiating immune responses against antigens entering the body through the mouth. They are also replication sites of some diseases. In spite of the importance of the palatine tonsils, there is no available data about the structure of these tonsils of the Egyptian water buffalo. Palatine tonsils of 10 clinically healthy buffalo bulls [2-3 years old] were obtained directly after slaughtering for human consumption. The tonsils were examined macroscopically and microscopically with light, and transmission electron microscopes. The tonsils were elongated kidney shape with a central hilus containing a single macroscopic opening leading to a small central cavity. Beside this hailer opening, there are a number of smaller macroscopical crypt openings [external crypts]. A number of macroscopic crypts were originating from the central cavity [internal crypts]. The tonsils were enclosed with a thin connective tissue capsule and septa which divided the tonsils into incomplete lobules. Each crypt was highly branched and extended deeply through the tonsils. These crypts were lined with stratified squamous non keratinized epithelium. Several lymphocytes infiltrated between the epithelial cells forming patches of reticular- and lymphoepithelium. The crypt lumen contains lymphocytes, neutrophils and erythrocytes. Lymphoid follicles with clear germinal centers extended under the epithelial surface. Diffuse lymphocytes extend in the narrow interfollicular region. High endothelial venules, interdigitating cells, macrophages and plasma cells were observed among the diffuse lymphocytes. Mucous glands were distributed among the lobules enclosed with connective tissue septa