Immunoelectron cytochemical localization of motilin in human duodenal enterochromaffin cells.

Two types of enterochromaffin cells can be demonstrated in the human duodenal mucosa by means of the Masson-Fontana reaction for argentaffinity applied to ultrathin sections. The 22-amino acid peptide motilin has now been localized exclusively to the duodenal type of enterochromaffin cell by immunoelectron microscopy. This cell occurs predominantly in the duodenum and upper jejunum. It is concluded that at least two types of enterochromaffin cells exist in the human gut mucosa and that they produce at least one biogenic amine as well as two peptides. Therefore they could provide a useful model for studies of the interrelationship of storage and release of amines and peptides.