Age-related changes and scar formations of perianal connective tissue.

Changes in perianal connective tissue were studied using specimens from juvenile cadavers and resected tissue from adults. The fibers of the anal sphincter muscles lie in a connective tissue mesh which anchors the muscle fibers, the anal mucosa and skin, and the entire anal canal. The connective tissue mesh is present in the newborn and has similar patterns in every age group, but the ratio of the amount of connective tissue/muscle tissue (C/M ratio) increases with age. The increase of the C/M ratio may have a role in the development of weakness of the sphincters and mucosal or rectal prolapse in the elderly. After injuries or operation no pure collagen scar formation was observed in the sphincter muscles, but there was an increase in the C/M ratio. In inflammatory bowel diseases, when severe anal stenosis is present, the connective tissue web and sphincter are intact and the scar formation is confined to the submucosal and subcutaneous layers.