Absence of mucosal atrophy in human small intestine after prolonged isolation.

Light and electron microscopic evaluation of segments of human jejunum (bypassed for 3 1/3 years in treatment of morbid obesity) and ileum (bypassed for 6 years as a Thirty-Vella fistula in treatment of postsurgical fistula) showed no obvious evidence of widespread mucosal atrophy. The findings contrast with those reported in experimental animals and in most human patients with ileal urinary conduits, where atrophy of the isolated segment is the rule. Perhaps nonluminal factors in the human subject are sufficient to maintain small intestinal mucosa for long periods in the absence of intestinal chyme.