OFDI images obtained from patients with a normal-appearing stomach and esophagus by endoscopy. (A) OFDI image of squamous mucosa. (B) Expanded view of A demonstrates a layered appearance, including the epithelium (e), lamina propria (lp), muscularis mucosa (mm), submucosa (sm), and muscularis propria (mp). Vessels are clearly identified in the submucosa (arrows). (C) OFDI image of gastric cardia. (D) Expanded view of C demonstrates vertical pit and crypts, regular, broad architecture, high surface backscattering, and diminished image penetration. Tick marks in A and C and scale bars in B and D represent 1 mm. Reprinted with permission from Suter MJ, et al..