Esophagus and the Barrett change !
- Organ
The esophagus is a muscular tube lined by layered flat cells; long-standing acid reflux can turn its lower lining into intestine-like tissue.
Updated 2026-11-01
See it in 3D: Esophagus
What it is
The esophagus carries food from pharynx to stomach. It is lined by non-keratinized stratified squamous epithelium, has mucous glands in its submucosa, and its muscle changes from skeletal above to smooth below. With chronic reflux the distal squamous lining can be replaced by columnar epithelium with goblet cells: Barrett esophagus, the precursor of esophageal adenocarcinoma.
Structure
- Mucosa: non-keratinized stratified squamous epithelium; a lamina propria; a thick muscularis mucosae.
- Submucosa: esophageal glands proper secreting mucus; mucous cardiac-type glands sit in the lamina propria near both ends.
- Muscularis externa: skeletal in the upper third, mixed in the middle third, smooth in the lower third.
- Outer layer: adventitia in the neck and thorax; a short serosa-covered segment below the diaphragm.
Step by step
- Acid and bile reflux repeatedly injure the distal squamous lining.
- Inflammation causes basal cell hyperplasia and longer papillae (reflux esophagitis).
- Stem cells start producing columnar cells better suited to acid.
- Intestinal metaplasia with goblet cells appears: Barrett esophagus.
- Low-grade and then high-grade dysplasia may develop.
- Invasive adenocarcinoma of the distal esophagus can follow.
Squamous cell carcinoma vs adenocarcinoma of the esophagus
| Feature | Squamous cell carcinoma | Adenocarcinoma |
|---|---|---|
| Usual site | Upper and middle thirds | Distal third, near the junction |
| Precursor | Squamous dysplasia | Barrett esophagus |
| Main risk factors | Tobacco, alcohol, very hot drinks | Chronic reflux, obesity, tobacco |
| Histology | Keratin pearls, intercellular bridges | Glands, mucin |
Clinical notes
- Barrett esophagus causes no symptoms itself; it is found on endoscopy with biopsy in people with long-standing reflux.
- Candida, herpes and cytomegalovirus esophagitis appear in immunosuppressed patients.
- Eosinophilic esophagitis: many eosinophils in the squamous epithelium, rings and furrows on endoscopy, often with atopy.
Test yourself
Think of the answer, then tap the question to see it.
What histological finding defines Barrett esophagus?
Columnar epithelium with goblet cells (intestinal metaplasia) replacing the normal squamous lining of the distal esophagus.
Which esophageal cancer arises from Barrett esophagus?
Adenocarcinoma, usually in the distal third near the gastroesophageal junction.
What type of muscle forms the muscularis externa of the upper third of the esophagus?
Skeletal muscle; the middle third is mixed and the lower third is smooth muscle.
Why can esophageal cancer spread early to neighbouring structures?
Most of the esophagus has no serosa, only a loose adventitia, so there is little barrier around it.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- The GI tract wall: mucosa, submucosa, muscularis, serosa; enteric plexuses
- Stomach: gastric glands, parietal and chief cells
- Cell adaptations: hypertrophy, hyperplasia, atrophy, metaplasia
Related conditions
Microorganisms
Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.
Sources: 23.3 The Mouth, Pharynx, and Esophagus - Anatomy and Physiology 2e | OpenStax (OpenStax (Rice University), 2022); Barrett esophagus: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2026); Gastroesophageal reflux disease: MedlinePlus Medical Encyclopedia (MedlinePlus (U.S. National Library of Medicine), 2026).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.