Histologic findings of the esophageal ulcer five minutes after the ESD. A sufficient volume of the submucosal layer remains in the ulcer bed with no evidence of damage to the proper muscle (striated muscle) layer. Neither inflammatory reaction nor reparative change is noted. Sq: squamous epithelium, MM: muscularis mucosa, SM: submucosa, PM: proper muscle layer (These symbols are used in the same way in the figures below). HE, original magnification × 40.