DEVELOPMENT OF THE EARLY MUCOSAL LESIONS IN EXPERIMENTAL INFLAMMATORYBOWEL-DISEASE - IMPLICATIONS FOR PATHOGENESIS

The purpose of this study was to better establish the morphologic basi s of the early mucosal lesions of experimental inflammatory bowel dise ase because understanding the development of these lesions has importa nt pathogenetic implications. Sprague-Dawley rats were given 1.5% hydr olyzed lambda-carrageenan orally for 30 days. This produced small inte stinal lesions which were then evaluated. Light microscopy showed an i ncreased amount of inflammatory cells in the gut wall with prominent P eyer's patches, microgranulomas, crypt abscesses, pin-point ulceration s, and a repair reaction. Scanning electron microscopy revealed pin-po int ulcerations in relation to Peyer's patches. Transmission electron microscopy, in addition to the above findings, showed disruptions of e nterocyte microvilli and terminal webs. Follicle-associated epithelium appeared to be a predilective site for the development of crypt absce sses and pin-point ulcerations. Enzyme-linked immunoadsorbent assays i ndicated that orally administered carrageenan elicited a systemic anti body response. Our results suggest that damage to enterocyte microvill i and terminal webs may be important early events in the morphogenesis of the lesions. (C) 1994 Academic Press, Inc.