Histomorphometrical and immunohistochemical study of cecal apex in rabbit (Oryctolagus cuniculus) and hamster (Mesocricetus auratus) with emphasis on microfolded cell

Fifteen mature rabbits and the same number of mature hamsters were conducted in this study to investigate the differences in the structure of the apical segment of the cecum in rabbits and hamsters, as well as to provide baseline information about the distribution and number of Mcells. Microscopic examination of the apex's rabbit and hamster cecal walls revealed four primary tunicae: mucosa, submucosa, muscularis, and serosa. In rabbits, the mucosa of the appendix was thrown with leaf-like folds lined with simple columnar epithelium with many goblet cells. Among these folds, there was a dome shape structure which is constructed from the aggregation of a large number of lymphoid follicles and lined with a special kind of epithelium which was termed follicle associated epithelium (FAE) and characterized by the presence of a large number of M cells, which were larger than the columnar cells and contained several lymphocytes. The immunohistochemical expression of M cells showed a strong reaction against GP2 in the cytoplasm and cell membranes, particularly in the dome epithelium of the rabbit appendix. In contrast, the reaction was weak or limited in hamsters. Concerning FAE of dome shape in the cecum of rabbit, most Mell were concentrated in the basal part of this epithelium, whereas the least expressed in the apex of the FAE. This study concluded that the apex of the rabbit cecum had more well-developed lymphoid tissue than the hamstercell count in rabbits was higher than that of hamsters, where the most occurrence of M cell was in the appendix of rabbits.