Crohn's disease: ultrastructure of interstitial cells in colonic myenteric plexus.

The role of the interstitial cells of Cajal (ICC) in chronic inflammatory bowel disease, i.e., ulcerative colitis (UC) and Crohn's disease (CD), remains unclear. Ultrastructural alterations in ICC in the colonic myenteric plexus (ICC-MP) have been reported previously in UC, but descriptions of ICC-MP and other interstitial cells in the myenteric region of the colon are lacking for CD. In the present study, we characterized the ultrastructure of interstitial cells, nerves, and glial cells in the myenteric region in Crohn's colitis (CC). In comparison with controls, varicosities of the myenteric bundles were dilated and appeared to be empty. Lipid droplets and lipofuscin-bodies were prominent in glial cells and neurons. ICC-MP were scanty but, as in controls, had caveolae, prominent intermediate filaments, cytoplasmic dense bodies, and membrane-associated dense bands with a patchy basal lamina. ICC-MP were similar in the various colonic regions. ICC-MP in CC showed no signs of degeneration or cytological changes. As in controls, fibroblast-like cells had abundant coated vesicles but lacked prominent intermediate filaments and caveolae. Macrophages also appeared as in controls. In comparison with ICC-MP in UC, the cytology of ICC-MP in CC were thus undisturbed. The ultrastructural differences between UC and CC might reflect pathophysiological differences of importance for understanding pathogenetic differences between CD and UC.