Histologic findings of the esophageal ulcer three weeks after the ESD. (A) The whole mount view of a HE preparation showing formation of a luminal ridge covered with the regenerated epithelium (arrow) without deformity of the outer contour of the proper muscle layer. The proper muscle layer of the luminal ridge area is thinned. (B) Low power view of the luminal ridge occupied by the thick layer of myofibroblastic cells (My) involving the inner layer of the proper muscle (PM). The ridge surface is covered with the regeneratied squamous epithelium (Sq). HE, original magnification ×40. (C) High power view of the myofibroblastic cells in the luminal ridge in the section stained for SMA. SMA-positive myofibroblastic cells, nuclei of which are plumper than those depicted in Figure 6C, are arranged in a parallel fashion and extending horizontally. Immunostain for SMA, original magnification ×400. (D) High power view of the proper muscle layer at the thinned portion, in which small immature myocytes are observed (arrows). HE, original magnification ×400.