Three-dimensional morphology of gut innervation in total intestinal aganglionosis using whole-mount preparation.

BACKGROUND: Total intestinal aganglionosis (TIA) is a rare form of Hirschsprung's disease (HD). The aim of this study was to examine the 3-dimensional morphology of the myentric plexus of the entire gastrointestinal tract in a newborn with total intestinal aganglionosis.
METHODS: Whole-mount preparations were made of the entire gastrointestinal tract using NADPH-diaphorase histochemistry and c-kit (a marker of interstitial cells of Cajal) immunohistochemistry.
RESULTS: Whole-mount preparations of the esophagus, stomach, and duodenum showed 3-dimensional morphology of the myenteric plexus forming a meshlike network of nerve fibers, connected to each other and to ganglia. There were large numbers of NADPH-diaphrase-positive nerve fibers between the muscle fibers in the circular muscle layer. In esophagus, stomach, and duodenum, c-kit-positive interstitial cells of Cajal (ICC) formed a 3-dimensional network between the two muscle layers and also were abundant within the circular muscle layer. In the jejunum, ileum, and colon, the myenteric plexus was absent and was replaced by hypertrophic nerve bundles that stained weakly with NADPH-diaphrase. Circular muscle layer completely lacked NADPH-diaphrase-positive nerve fibers. The c-kit-positive ICCs in the jejunum, ileum, and colon were sparse and localized mainly around the nerve trunks between the circular and longitudinal muscle layers.
CONCLUSIONS: Whole-mount preparation is an elegant 3-dimensional technique in which the relationship of branching and interconnecting nerve fibers to each other and to muscle can be seen clearly. Absence of myenteric plexus, lack of nitrergic innervation, and depletion of interstitial cells of Cajal in the bowel wall throughout the small and large bowel contribute to the inability of the smooth muscle to relax, thereby causing lack of peristalsis in TIA.