Digestive disorders

II./1.3.: Regional histological characteristics

II./1.3.1.: Appendix

The appendix is basically a vestigial part of the colon, therefore it shows the typical colonic wall structure. However, there are some important differences: it has a much narrower diameter – therefore its lumen is also narrower. Its most important characteristic is the large number of lymphatic follicles situated in the tela submucosa and in the lamina propria mucosae, therefore the appendix is called the "tonsil" of the large intestine or tonsilla processus vermiformis as well. These lymphatic follicles are found along the entire cross section of the appendix (Fig. 3.). As mentioned above, appendix has no teniae, but presents a continuous outer longitudinal smooth muscle layer. The tela subserosa and the tunica serosa are continued in the mesoappendix, there the sections of larger vessels serving the blood supply of the organ are also clearly visible

Figure 3.: Histology of the appendix (1) surface epithelium with goblet cells; (2) crypts of Lieberkühn  (3) lymphatic follicles; (4) tunica muscularis (propria); (5) tunica serosa (6) mesoappendix

II./1.3.2.: Anal canal

It has the following parts starting from the oral direction:

• 1) columnar zone: 8-10 vertical folds are seen on the mucous membrane (anal columns of Morgagni), between them depressions (anal sinuses of Morgagni). These mucosa sinuses are lined by simple columnar epithelium, the folds are covered by stratified squamous, non-keratinized epithelium. The second part:

• 2) haemorrhoidal zone: lined by stratified squamous, non-keratinized epithelium; sebaceous glands and internal haemorrhoidal venous plexuses are discernible in the connective tissue under the epithelium. The lowest (aboral) part:

• 3) cutaneous zone: covered by stratified squamous, slightly keratinized epithelium (like the nearby skin), heavily pigmented. The underlying connective tissue (dermis or corium) contains sweat and sebaceous glands. In the perianal skin circumanal glands (apocrine scent glands) are located.