Skip to content
- Mucosa follows a simple pattern: epithelium + lamina propria + muscularis mucosae, then submucosa, muscularis propria, adventitia/serosa.
- Crypt/villus balance and gland type change by segment—use the surface architecture first, then cell mix.
- Lymphoid tissue is common (Peyer patches, solitary follicles); do not overcall reactive lymphoid aggregates.
- Muscularis mucosae and submucosal (Meissner) vs myenteric (Auerbach) plexi mark layer boundaries.
- Stratified squamous non-keratinized; thick muscularis mucosae near GE junction.
- Submucosal glands proximally; abrupt change to gastric-type mucosa at Z-line.
- Foveolar mucus cells on surface/pits; gland type varies by region (cardia mixed, body oxyntic, antrum mucous).
- Muscularis mucosae thin and regular; no Paneth cells in normal stomach.
- Duodenum: villi + Brunner glands in submucosa; mix of absorptive cells, goblet cells, Paneth cells.
- Jejunum: tall villi, no Brunner glands; abundant plicae circulares.
- Ileum: shorter villi, Peyer patches; Paneth cells still present.
- No villi; straight crypts with many goblet cells, scattered endocrine cells, surface absorptive cells.
- Muscularis propria with taeniae coli (colon); appendix has lymphoid tissue through wall.
- Columnar → anal transitional → squamous; evaluate for orderly maturation and intact basement membrane.
- Upper GI: CK7+/CK20− pattern typical for stomach; MUC5AC (foveolar), MUC6 (pyloric/Brunner).
- Small bowel/colon: CDX2+, CK20+, SATB2+ (colon), abundant MUC2 in goblets; Paneth cells lysozyme+.
- Squamous lower esophagus/anal canal: p63/p40 in basal layers, CK5/6+, no keratin pearls in normal mucosa.
