Histology
The three sections of the small intestine look similar to each other at a microscopic level, but there are some important differences. The parts of the intestine are as follows:
| Layer | Duodenum | Jejunum | Ileum |
| serosa | 1st part serosa, 2nd - 4th adventitia | normal | normal |
| muscularis externa | longitudinal and circular layers, with Auerbach's (myenteric) plexus in between | same as duodenum | same as duodenum |
| submucosa | Brunner's glands and Meissner's (submucosal) plexus | no BG | no BG |
| mucosa: muscularis mucosae | normal | normal | normal |
| mucosa: lamina propria | no PP | no PP | Peyer's patches |
| mucosa: intestinal epithelium | simple columnar. Contains goblet cells, Paneth cells | Similar to duodenum. Villi very long. | Similar to duodenum. Villi very short. |
Read more about this topic: Small Intestine