ULTRASTRUCTURE OF INTERSTITIAL-CELLS OF CAJAL AT THE COLONIC SUBMUSCULAR BORDER IN PATIENTS WITH ULCERATIVE-COLITIS

Background & Aims: Submuscular interstitial cells of Cajal (ICC) are p utative pacemaker cells of the colonic external muscle, Although motil ity disturbances and smooth muscle dysfunction ave prevalent in patien ts with ulcerative colitis (UC), ICC have never been studied in this d isease, The aim of this study was to examine the ultrastructure of sub muscular ICC in UC, Methods: Transmission electron microscopy of the c olonic submuscular region was performed using specimens from 4 adult p atients who had undergone resection for severe UC, The specimens weve compared with similarly processed control samples, Results: ICC often showed multiple secondary lysosomes, large confluent lipid bodies, and disrupted aggregates of vacuolated glycogen clusters, Intermediate fi laments showed margination and clumping, Intramuscular and submucosal nerve terminals were often swollen. Macrophages were frequent, often c lose to nerves and ICC. Muscle cells of the innermost circular layer, fibroblast-like cells, and glial cells appeared undisturbed. Other inf lammatory cells were inconspicuous, Conclusions: Alterations of ICC ul trastructure are present in the submuscular pacemaker region of the co lon in patients with severe UC, The changes in ICC may result from pri mary damage or changes secondary to defective muscular function, or th ey may reflect neuroimmune-mediated metabolic responses. It is suggest ed that ICC are actively involved in the pathogenesis of motility dist urbances in UC.