Layers of Bowel Wall

  • Lumen (interior surface of colon "tube")
  • Mucosa
  • Surface epithelium
  • Lamina propria or basement membrane—dividing line between in situ and invasive lesions
  • Muscularis mucosae
  • Submucosa—lymphatics; potential for metastases increases
  • Muscularis propria
  • Circular layer
  • Longitudinal layer—in three bands called taenia coli
  • Subserosa—sometimes called pericolic fat or subserosal fat
  • Serosa—present on ascending, transverse, sigmoid only (also called the visceral peritoneum)
  • Retroperitoneal fat (also called pericolic fat)
  • Mesenteric fat (also called pericolic fat)
Illustration of the layers of the bowel wall.