Intramucosal nerve cells in human small intestine.

We investigated the intramucosal nerve cells of the human small intestine with histochemical methods to demonstrate nicotinamide adenine dinucleotide diaphorase and acetylcholinesterase and with morphometry. Intramucosal neurons appeared as solitary cells or in small groups, especially in the ileum. Most intramucosal nerve cell bodies were round or oval; some were flat or spindle-shaped. They mostly lay close to the muscularis mucosae, but some were located within the muscularis mucosae and others were some distance away from it. The processes of some mucosal neurons projected towards the submucosa. Most mucosal nerve cells showed acetylcholinesterase activity. The frequency distribution of nerve cell profile areas in the intramucosal cells in the duodenum differed from that of cells in the ileum (P < 0.001). There were more large mucosal nerve cells in the mucosa of the duodenum than in the ileum. There was no significant difference between the frequency distributions of cell profile areas of cells of the mucosa and cells of Meissner's and Henle's plexuses in the same region. We conclude that intramucosal nerve cells, similar to those of the submucosal plexus, exist in the human small intestine. The size of intramucosal nerve cell profiles differs between the duodenum and ileum. This is consistent with their possible different functions.