Dysplastic nitrergic neurons in the rectum of a patient with rectal ectasia.

We present a histochemical study of resected colon from a 13-year-old boy diagnosed with rectal ectasia. Laminar preparations and sectioned tissue of rectum were assayed histochemically for nitric oxide (NO) synthase activity by reducing nitro blue tetrazolium salt in the presence of the cofactor NADPH. Tissue preparations displayed intensely labelled neurons and fibers throughout the gut wall. Laminar preparations of Meissner's plexus showed a hyperplasia of ganglia and NO-related neurons throughout the length of the resected rectum compared with normal bowel. Sectioned tissue of the Auerbach's plexus demonstrated a normal number of ganglia and NO-related neurons. As well, the ectatic bowel showed a proliferation of nerve fibers in keeping with the degree of circular smooth muscle hypertrophy. This proliferation may represent a reactive phenomenon secondary to the functional obstruction. The NO histochemical technique may form the basis of further investigations in defining the cause of this functional obstruction.