Light and electronmicroscopy of the bowel in an unusual form of Hirschsprung's disease

In a histological and histochemical study of multiple biopsies of unaffected segments of the bowel from 15 patients with Hirschsprung's Disease (H.D.), the AChE or non-specific esterase and the NADPH tetrazolium reductase enzyme reactions proved to be useful in identification of myenteric plexus islands; and acid phosphatase for the delineation of individual neurones. In the affected segment (usually aganglionic), this myenteric plexus tissue was not reactive for esterase, but individual nerve fibres among muscle fibres of the two muscle coats showed the enzyme product in a third of the cases. Fine structural study of biopsies from a typical case of H.D., showed normal looking axons and Schwann cytoplasm with terminals bearing both andrenergic and cholinergic vesicles in the unaffected colon, smooth muscle fibres with normal fine structure in all parts of the bowel, and loss of neurons with myenteric plexus replaced by nerve fibre groups in the affected rectosigmoid. One patient clinically presenting as a case of severe H.D., with histologically and histochemically normal myenteric and submucous ganglion cells, and not responding to resection of the bowel, showed degeneration of the unmyelinated axons with prominent Schwann cytoplasm, depleted cholinergic but persistent adrenergic vesicles, and markedly thinned and degenerating smooth muscle fibres and myofilaments, suggesting either a primary disorder of muscle tissue of the colon or, less likely, a denervation atrophy with secondary degeneration of the smooth muscle fibres.