Structural organization of enteric nervous system in human colon.

The organization of the Enteric Nervous System (ENS) was studied in the human colon. Fragments of the whole colonic wall were either routinely processed or Zinc-Iodide Osmium impregnated. Single-layer preparations were also obtained from some of the Zinc-Iodide Osmium-impregnated specimens. The results showed some differences in the organization of human colonic ENS from that of other mammals. In fact, the human submucous plexus was made up of three interconnected ganglionated networks arranged along three different planes. With respect to the myenteric plexus, its ganglia were large sized and irregularly shaped. Moreover, during the microdissection of the colonic wall, we found the absence of a cleavage plane between the circular and longitudinal muscle layers; on the other hand the cleavage plane between mucosa and submucosa was not immediately below the muscularis mucosae, but slightly deeper, since the innermost part of the submucosa remained adhering to overlying layers.