The comparative pathology of the primate colon.

This survey has revealed further close similarities between the pathology of certain colonic diseases in humans and primates. The changes taking place in acute inflammations of varying severity confined to the lamina propria are virtually identical as are those seen in the healing process. In primates chronic inflammatory processes caused by protozoa resemble those in humans very closely. Microherniation of mucosal glands through the muscularis mucosae were found in a wide range of species. Evidence pointed to such herniations playing an important role in the spread of inflammatory diseases from the lamina propria into the submucosa by affording the aetiological agent access through the muscularis mucosae. No case of adenocarcinoma was found in this survey and the cause for the striking difference in incidence of this disease in human and primate colons is discussed.