Expansion
Each region has a characteristic epithelium and glandular pattern
Expansion
| Region | Identifying features |
|---|---|
| Oesophagus | Stratified squamous non-keratinised; mucous glands in submucosa |
| Stomach | Gastric pits and glands; parietal and chief cells in body, G cells in antrum; no villi |
| Duodenum | Villi plus Brunner glands in the submucosa (unique) |
| Jejunum | Tallest villi, prominent plicae circulares, no Brunner glands, few Peyer patches |
| Ileum | Peyer patches in the submucosa, shorter villi, many goblet cells |
| Colon | No villi, straight crypts, abundant goblet cells |
| Rectum and anal canal | Colonic type, changing to stratified squamous below the pectinate line |
Brunner glands secrete alkaline mucus to neutralise gastric acid, which is why they are confined to the duodenum, and predominantly the proximal part.
Peyer patches are aggregated lymphoid follicles with overlying M cells, positioned in the ileum where the bacterial load is highest.
The absence of villi with abundant goblet cells is the quickest way to identify colon, and the presence of villi immediately excludes both stomach and colon.
Villous atrophy with crypt hyperplasia in the duodenum is the hallmark of coeliac disease.