ABSTRACT
Histologically, HD is characterized by the absence of ganglionic cells in the myenteric and submucous plexuses and the presence of hypertrophied nonmyelinated nerve trunks in the space normally occupied by the ganglionic cells (Fig. 55.2). The aganglionic segment of bowel is followed proximally by a hypoganglionic segment of varying length. This hypoganglionic zone is characterized by a reduced number of ganglionic cells and nerve fibers in myenteric and submucous plexuses.
