title: The pathogenesis of hemorrhoids.
abstract: The structure of the anal canal was examined in histology slides. Hemorrhoids are normal features of the human anatomy. They are pads that bulge into the lumen. Hemorrhoids have three parts: 1) the lining, which can be mucosa or anoderm; 2) the stroma with blood vessels, smooth muscle, and supporting connective tissue; and 3) the anchoring connective tissue system, which secures the hemorrhoids to the internal sphincter and the conjoined longitudinal coat. The anchoring and supporting connective tissue system deteriorates with aging. The hemorrhoids not only bulge, but descend into the lumen. This becomes observable in the third decade of life, with individual differences. The veins become distended as they lose their support. The descended loose lining becomes more sensitive to pressure from straining and to trauma from the stool. There can be a stasis in the veins, with clot formations and swelling, or erosions of the lining, with bleeding. The hemorrhoids become symptomatic.
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D001003:Anal Canal / Q000098:blood supply / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003238:Connective Tissue / Q000473:pathology*; D005260:Female; D006484:Hemorrhoids / Q000473:pathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged