<prompt> Hirschsprung colon is due toMuscle atrophy in muscularis mucosaLoss of intrinsic enteric plexusesLoss of extrinsic nerve supplyNone  <response>: Hirschsprungs Disease Congenital Megacolon The term megacolon is used for any form of marked dilatation of the entire colon or its segment may occur as a congenital or acquired disorder. Congenital form: congenital absence of ganglion cells in the bowel wall enteric neurons is called Hirschsprungs disease. As a result, the aganglionic segment remains contracted. Gross: shows 2 segments, a distal narrow segment that is aganglionic and a dilated proximal segment that contains normal number of ganglion cells Microscopy: distal narrow segment shows total absence of all the three plexus Auerbachs, Heres, and Meissners plexus TEXTBOOK OF PATHOLOGY 6TH EDITION HARSH MOHAN PAGE NO:580 IMAGE REFERENCE: 