Histochemical, immunocytochemical and ultrastructural data on the innervation of the smooth muscle of the large intestine in Hirschsprung's disease.

The frequency of occurrence of the adrenergic, cholinergic, 5-hydroxytryptamine (5-HT)-, substance P (SP)-, methionine-enkephalin (met-Enk)- and somatostatin (SOM)-immunoreactive fibres innervating the smooth muscle of the large intestine in Hirschsprung and control children was compared. It was observed a higher frequency of catecholamine-fluorescence, acetylcholinesterase-positive and SOM-immunoreactive fibres in the muscularis externa and muscularis mucosa of the aganglionic segment in Hirschsprung gut as compared to that in the sigmoid colon and rectum in controls. In contrast, the frequency of SP-, met-Enk- and 5-HT-immunoreactive fibres in the aganglionic segment in Hirschsprung gut was lower than that in the controls. Ultrastructurally the cholinergic and adrenergic fibres occurred more often in the aganglionic segment in Hirschsprung gut than in the controls. A treatment with 6-OHDA and a fixation by Tranzer and Richards technique was used to confirm the nature of the adrenergic fibres. The p-type fibres occurred infrequently in the aganglionic segment of Hirschsprung gut. The results suggest that the change in the frequency of the nerves containing inhibitory transmitters may play an important role in the pathogenesis of Hirschsprung's disease.