Histologic findings of the esophageal ulcer one week after the ESD. (A) The whole mount view of a HE preparation. The regenerative squamous epithelium is observed at the ulcer edges (arrows). The thickness of the proper muscle layer is still preserved. (B) In middle power view of the ulcer bed, myofibroblastic cells (My) are identified arranged in a parallel fashion and extending horizontally forming bundles between the edematous granulation tissue of the ulcer bed surface (Gr) and the proper muscle layer (PM), partly occupying the superficial part of the PM. HE, original magnification ×100. (C) High power view of the area including the upper proper muscle layer and the lower myofibroblastic cell layer in the section stained for SMA. Transition between SMA-positive spindle-shaped myofibroblastic cells (arrowheads) and SMA-positive small striated myocytes (arrows) is suggested. Immunostain for SMA, original magnification ×400.