The Microanatomy of the Palatine Tonsils of the One‐Humped Camel (Camelus dromedarius)

Abstract

Tonsils form a first line of defense against foreign antigens and are also a route of entry and a replication site for some pathogens. The palatine tonsils are the largest of all the tonsils. Despite their general importance, little is known about the microanatomy of the palatine tonsils of the one-humped camel. Palatine tonsils of 10 clinically healthy male camels were obtained directly after slaughtering for human consumption. The tonsils were examined macroscopically and by light, scanning, and transmission electron microscopy. Palatine tonsils had the unique form of several spherical macroscopic nodules protruding into the pharyngeal lumen. These spherical masses were numerous and close together in the lateral oropharyngeal wall, with a few solitary nodules in the dorsal wall. Each nodule had one or two apical openings to crypts, and was enclosed by an incomplete connective tissue capsule and covered apically with stratified squamous keratinized epithelium. The tonsillar crypt was lined with stratified squamous non keratinized epithelium. Several lymphocytes infiltrated the epithelial layer, forming patches of reticular epithelium. Lymphoid follicles with obvious germinal centers extended under the epithelial surface. Diffusely localized lymphocytes were seen in the interfollicular region. High endothelial venules, dendritic cells, macrophages, and plasma cells were observed among these lymphocytes. The unique arrangement of palatine tonsils in separate units with individual crypts results in a very large surface exposed to antigen and indicates a significant immunological role of palatine tonsils in the camel.