The Anorectal Myenteric Plexus: Its Relation to Hypoganglionosis of the Colon

To define the anatomy of the distal anorectal myenteric plexus more clearly, specimens from this region obtained at autopsy from 25 patients ranging from premature infants to children six years of age were studied. A distal zone characterized by a paucity of ganglion cells and the presence of nonmyelinated nerve trunks was identified. This zone is similar in appearance to areas of hypoganglionosis occurring in association with various forms of Hirschsprung's disease. The extent of this zone is quite variable but tends to increase slightly with age. It may extend up to 2.5 cm. proximal to Hilton's line or 2 cm. proximal to the pectinate line. In performing a rectal biopsy for the diagnosis of Hirschsprung's disease care must be taken to remain proximal to this zone. Interpretation of the rectal biopsy should not rest solely upon the identification of ganglion cells but must include an evaluation of the entire morphology of the myenteric plexus.