The innervation of human bowel mucosa and its alterations in Hirschsprung's disease using a whole-mount preparation technique

Abstract

 The innervation of the human bowel wall and its structural and functional changes in Hirschsprung's disease (HD) are well-recognised. The luminal surface of the bowel acts as a multifunctional barrier, and modifications in its physiochemical properties can result in serious complications such as enterocolitis (EC). The whole-mount preparation (WMP) technique produces a three-dimensional (3D) picture to better demonstrate the neuronal networks and the relationship of branching and interconnecting nerve fibres to each other. The aim of this study was to investigate the innervation of the mucosal layer in normal and HD bowel using a WMP immunohistochemistry technique in order to better understand the pathophysiology of HD. Full-thickness bowel specimens were collected from 9 HD patients at pull-through operation. Normal control small- and large-bowel specimens were collected from 10 patients at the time of bladder augmentation. Suction rectal biopsies from 8 patients with chronic constipation and 2 patients with HD were also included in this study. A WMP of the mucosal layer was made and stained with various neuronal markers (S100, PGP 9.5, and LlCAM) using fluorescein immunohistochemistry. PGP 9.5, S100, and LlCAM immunofluorescence staining of the normal mucosa demonstrated a characteristic 3D meshlike neuronal network of uniform thickness surrounding the crypts. In the aganglionic bowel S100, PGP 9.5, and LlCAM-positive meshlike networks were replaced by thick nerve trunks in the muscosa without any interconnecting network. The present study demonstrates for the first time the 3D morphology of mucosal innervation in normal and aganglionic bowel. The WMP technique clearly demonstrated that the mucosal innervation in HD is morphologically abnormal, and this may adversely influence secretory and absorptive functions of the bowel. WMPs using suction rectal biopsy specimens may be a useful additional technique to diagnose HD.