This segment of colon shows an upper dilated portion and a lower narrow portion. The dilated
portion shows a thicker wall due to muscular hypertrophy. The upper part of the narrow segment
is thin and the mucosa is flattened; this represents a ganglionic portion of the bowel and is some 2
cm in length. The lower portion of the specimen appears essentially normal. This is presumably a
surgically resected specimen where the narrow segment has been removed and the normal segments
anastomosed. The history of the specimen is not known but it dates back to 1953.