Staining for fibrosis and for neuronal structures. Panels A-C. Trichrome staining. The control (A) and sections from case 1 (B) showed no increase in fibrosis, whereas sections from case 2 (C) showed an increase in fibrosis in both muscle layers and along the myenteric plexus. Scale bar 200 μm. Panels D-F. PGP 9.5 immunoreactivity. PGP9.5 immunoreactivity as a marker for neuronal structures was normal in control (D) and in case 1 (E). There was a decrease in PGP 9.5 immunoreactivity in both the muscle layers and the myenteric plexus in sections from case 2 (F) suggesting a loss of neuronal structures. Panels G-I. Tyrosine hydroxylase immunoreactivity. Tyrosine hydroxylase immunoreactivity was normal in the control (G). Sections from case 1 (H) showing normal tyrosine hydroxylase immunoreactivity around the myenteric plexus with a lsight decrease in tyrosine hydroxylase immunoreactivity in the muscle layers. Sections from case 2 (I) showed a marked loss of tyrosine hydroxylase immunoreactivity in all regions suggesting a loss of extrinsic nerve fibers. Scale bar 100 μm. Circular muscle (CM), myenteric plexus (MP), longitudinal muscle (LM).