Immunocytochemistry of serotonin-containing nerves in the human gut.

An immunocytochemical technique, using L-tryptophan enhancement and paraformaldehyde fixation, has been successfully applied for the demonstration of serotonin-containing neurons in the human enteric nervous system. Throughout the intestine, serotonin-immunoreactive nerves were mainly detected in the myenteric plexus and, to a smaller extent, in the submucous plexus, while hardly any nerve fibres were seen in the mucosa. This approach provides a useful tool for the investigation of neuropathological conditions of the gut.