[Ultramicroscopic study of the colonic mucosa infected by E. histolytica].

In eight guinea pigs, trophozoites of E. histolytica HM-2 IMSS strain grown in plurixenic conditions were inoculated in their cecum. Two died two days after inoculation; the remaining si- were sacrificed six days afterwards. Tissue samples were obtained from amebic lesions and nearby areas. At ultramicroscopic level it was observed that epithelial cells in contact with the parasite had short and/or scanty microvilli, swollen mitochondria, ER dilatation and absence of the terminal bar. When trophozoite was within the epithelium, cells in contact with it were destroyed; basement membrane was elongated before it was broken up by the parasite. In the lamina propria trophozoites were found close to glands, blood capillaries and in contact with macrophages, lymphocytes, and most cells. No polymorphonuclear cells were identified in all samples studied. Capillaries were congestive, lacking polymorphonuclear cells. It was postulated that probably initial colonic mucosa lesion in amebiasis depends solely upon parasite action.