Electron microscopic observations in infantile hypertrophic pyloric stenosis (IHPS).

Electron microscopic observations of the pyloric parasympathetic ganglia in IHPS have demonstrated, contrary to previous reports, that no abnormalities exist in the neurons and interstitial cells of the plexuses or the cells of the pyloric smooth muscles. The significance of finding a small number of altered large axons is unclear. In view of finding essentially normal morphology, a "functional" etiology of this disease is suggested.