Studies of Human Amebiasis: II. Light and electron-microscopic observations of colonic mucosa and exudate in acute amebic colitis

Light and electron-microscopic examination of sigmoid colonic mucosal biopsies obtained from individuals with well documented amebic colitis demonstrated a diffuse inflammatory process with and without superimposed focal ulcerations. Amebae were rarely found except at the superficial portions of ulcers. The findings of this study suggest that the mucosal inflammatory process precedes focal epithelial ulceration and may be the result of toxic product(s) released by amebae. Interglandular surface epithelium appeared to be lysed prior to invasion by trophozoites. It is postulated that release of lysosomal- like vesicles from the surface membrane of amebae, or rupture of entire organisms, may represent means by which toxic products are liberated from amebae.