ELECTRON MICROSCOPICAL STUDY OF CHRONIC ULCERS OF COLON IN RATS

  • 1 January 1977
    • journal article
    • research article
    • Vol. 58  (1) , 63-77
Abstract
Chronic colonic ulcers in the rat were produced by the administration of H2O2 enema. Lesions of up to 10 mo. duration were obtained by this method and a selection was examined ultrastructurally in order to reveal causes for the chronicity of the lesions. From previous work it appeared there was no failure of epithelial migration from the edge of the wound. The majority of cells at the ulcer margins demonstrated features of regeneration similar to those seen in other tissues, and that there were no specific changes concomitant with chronic ulceration. The majority of epithelial cells at the ulcer edge showed features of differentiation which indicated there was no obvious fault in this process so essential to the basic requirements of tissue repair. It was possible that chronicity was produced by a failure of the epithelio-mesenchymal interaction mechanisms which, potentiated by an ischemia resulting from submucosal vascular damage, resulted in the consequential death of migrating epithelial cells. This was supported by the appearance of a squamous metaplasia in the healing lesions, a process which is commonly attributed to a chronic inflammatory response which may be induced by a relative vascular insufficiency.