Left: View of esophageal wall through a side-viewing instrument. Island of columnar epithelium found in the distal esophagus of a 50 year-old woman undergoing ERCP.

Center: Island of columnar epithelium above the columnar segment of Barrett's disease in a 71 year-old man with chronic gastroesophageal reflux symptoms.

Right: Thickened, thread-like residual squamous epithelium within the columnar area of short-segment Barrett's disease in an 18 year-old man with gastroesophageal reflux symptoms.

Right: Islands of squamous epithelium within the segment of Barrett's in a 64 year-old woman.