Immunohistochemical reactivity of neuropeptides in plastic-embedded semithin sections of the myenteric plexus in infantile hypertrophic pylorus stenosis.

Pyloric biopsies obtained at pyloromyotomy from 46 infants were studied by light and electron microscopy and compared to 8 autopsy control cases without any evidence of infantile hypertrophic pyloric stenosis (IHPS). A positive family history of this disorder was recorded in 8 cases (2 girls and 6 boys). The most frequent changes in the myenteric plexus comprised axonal alterations. In glial cells, cytoplasmic vacuolisation or an increase of intermediate filaments occurred. In ganglion cells, vacuolisation of perikaryal cytoplasm or dense bodies were observed. No obvious differences were seen between sporadic and hereditary cases. In addition to these fine structural alterations, immunohistochemistry in 6 IHPS cases and 4 controls revealed differences in the distribution of substance P, bombesin, calcitonin gene related peptide and enkephalin-like immunoreactivity within the myenteric plexus between IHPS and control cases. The immunoreactivity, however, was unevenly distributed from case to case and even within individual cases. The reduction of immunoreactivity corresponded, at least in part, to an increase of neurofilaments or abnormal organelles within axons. Increased immunoreactivity was apparently related to focal accumulation of dense cored vesicles noted in the preceding study. It is suggested that these and other changes reported interfere with the normal gastrointestinal reflex mechanisms leading to intestinal obstruction.