Sections from the dilated segment. In addition to the inner circular (IC) and longitudinal (L) layers, there is an extra outer smooth muscle layer (OC). Ganglia and nerves (stars) (b) and interstitial cells of Cajal (arrows) (c, d) are located on both sides of the longitudinal muscle. (a) Hematoxylin and eosin (H&E), (b) Masson trichrome, and (c-d) CD117 (c-kit). (a-b) Original magnification × 10. (c-d) Original magnification × 40.