Unique microanatomy of ileal peyer's patches of the one humped camel (Camelus dromedarius) is not age-dependent.

The Peyer's patches (PP) have been intensely investigated in several species because this is an important entry site for antigens and infectious agents. There are many PP in the jejunum, and in some species such as ruminants, carnivores, and omnivores, a different continuous PP is found in the terminal ileum. This PP disappears with age in these species studied. So far the ileal PP (IPP) has only been examined in the camel by light microscopy. Therefore, the localization of ileal Peyer's patches in the dromedary camel at different ages, as well as the histology and ultrastructures were now investigated. The IPP were characteristically seen as dark rose-colored isolated structures in the shape of a cup, arranged in three irregular rows. The central row was antimesenteric. Each patch was formed by several mainly elongated dome regions flanked by intestinal villi. In cross-sections these domes appeared as short, wide villi. The domes were formed from lymphoid follicles covered with a typical dome-associated epithelium of enterocytes and M cells without any goblet cells. The M cells showed variable appearance depending on the functional status. The lymphoid follicles expressed clear germinal centers. High endothelial venules were localized in the interfollicular region. In contrast to other species the IPP were still present with a comparable macroscopic and histological structure in camels of 25 years of age.