2. Neurohistoloical Studies of the Anus among Japanese

Abstract

The nerve supply of the lining tissue of the anal canal had three origins.The first was the MEISSNER'S plexus, which laid only upper end of the anal canal in foetus and newborn.The second was extrinsic nerve fibers coming from the pelvic space to pass through the longitudinal muscle and pass through/under the internal sphincter. The fibers were numerous in foetus but diminished with getting older.The third was extrinsic nerve fibers which passed through the external sphincter, under the internal sphincter, and went upward as far as the dentate line making nerveplexus and sensory endings.Sensory endings consisted of free nerve ending, organized ending and hair plexus. Free endings were found in foetus as well as in adult. Organized endings were found in subjects aged of four years and adult: many of them were "glomerular type" endings and a few genital corpuscle. Special baroreceptors such as arborised ending (SUNDER-PLASSMANN) were found especially adjacent to the hemorrhoidal plexus. At anal valve, some nerve fibers, showed extensive neurofibrillar swelling which presumably play some role to extend the sensory area of nerve element.Out of the intersphincteric groove was shown to be innervated by fibers which passed under the external sphincter.