title: Distribution of Peyer's patches in the distal ileum.
abstract: OBJECTIVE
  Peyer's patches play a major role in intestinal immunity, are portals of entry for significant pathogens, and may be important in Crohn's disease. Whereas their microscopic anatomy and immune function are well described, surprisingly little is known of their macroscopic anatomy and distribution. Our aim was to assess their number, area, and distribution in the normal distal ileum, with particular reference to patient age.
  
  
  METHODS
  Distal ilea (200 cm) obtained at autopsy from 55 adults without intestinal disease were opened along the mesenteric border, fixed in acetic acid, and transilluminated. Peyer's patches were counted, and the length, breadth, and distance from the ileocecal valve were recorded.
  
  
  RESULTS
  Patches were most numerous in the terminal 10-15 cm where they formed a lymphoid ring. More proximal patches were oval, antimesenteric, and irregularly spaced. By area, 46% of patch tissue occurred in the terminal 25 cm. The mean number of patches ranged from 29.4 +/- 5.4 in the youngest group studied, to 19.0 +/- 3.0 in the oldest. Total patch area was greatest in the group aged 21-30 (47.4 +/- 1.0 cm2).
  
  
  CONCLUSIONS
  Peyer's patches are concentrated in the distal 25 cm of ileum but extend proximally for 200 cm. The variation in their size, shape, and distribution in different individuals is greater than often appreciated and may influence the presentation of diseases centered on these structures.
authors.affiliation: Department of Pathobiology, University of Connecticut, Storrs, Connecticut, USA. herbert.vankruiningen@uconn.edu
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Van Kruiningen
authors.forename: A Brian
authors.initials: AB
authors.lastname: West
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Freda
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Holmes
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D003424:Crohn Disease / Q000276:immunology; D005260:Female; D006801:Humans; D007082:Ileum / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D010581:Peyer's Patches / Q000276:immunology / Q000473:pathology*