Ontogeny of peptide-containing neurons in human gut--an immunocytochemical study

Neurons containing enkephalin, substance P (SP), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), galanin, calcitonin gene-related peptide (CGRP), peptide histidine isoleucine (PHI) or gastrin-releasing peptide (GRP) are known to occur in the human intestinal tract. The knowledge of the ontogeny of these neurones is, however, limited. Intestinal specimens from 24 human foetuses with gestational ages varying between 8 and 40 weeks were examined by immunocytochemistry. No peptide-containing neurones could be detected before the 14th week of gestation after which a rapid development was seen. Generally, peptide immunoreactivity was first noted in the myenteric ganglia and somewhat later in the other layers of the intestinal wall. There was no major difference between the peptides studied or between different parts of the intestinal tract with respect to time of appearance.