Which histological feature best distinguishes the mucosa of the stomach from that of the small intestine?

Explanation

## Distinguishing Gastric from Small Intestinal Mucosa ### Key Structural Differences **Key Point:** The stomach mucosa is characterized by **gastric glands** (fundic glands) containing specialized secretory cells — parietal cells (HCl, intrinsic factor) and chief cells (pepsinogen) — which are entirely absent in the small intestine. ### Comparative Histology Table | Feature | Stomach | Small Intestine | | --- | --- | --- | | **Epithelium** | Simple columnar (mucus-secreting) | Simple columnar with brush border | | **Glands** | Gastric glands (parietal, chief, mucous) | Crypts of Lieberkühn (enterocytes, Paneth cells) | | **Villi** | Absent | Present (increase surface area) | | **Brush border** | Absent | Present (microvilli on enterocytes) | | **Peyer's patches** | Rare/absent | Present (especially ileum) | ### High-Yield Discriminator **High-Yield:** The presence of **parietal cells and chief cells** in gastric glands is pathognomonic for stomach mucosa. These cells are never found in the small intestine. Parietal cells are identifiable by their large size, central nucleus, and abundant eosinophilic cytoplasm due to rich mitochondria and rough ER (for HCl and intrinsic factor synthesis). ### Clinical Pearl **Clinical Pearl:** Intestinal metaplasia of the stomach (replacement of gastric glands with intestinal-type glands) is a precancerous lesion and indicates loss of this discriminating feature — a key finding in chronic gastritis and gastric cancer risk stratification. ### Why Other Options Are Incorrect - **Villi with brush border:** While characteristic of small intestine, they are NOT present in stomach, so this does not distinguish; it eliminates stomach entirely. - **Peyer's patches:** Found in small intestine (especially ileum) but also occasionally in stomach; not a reliable discriminator. - **Simple columnar epithelium without glands:** Both stomach and small intestine have simple columnar epithelium; this is not discriminating.