The intestinal mucous membrane is an complex that covers the largest part of the small and large intestine. It is a part of the intestinal barrier, important for immune defence and prevents the self-digestion of the intestine (Vancamelbeke & Vermeire, 2017).
In the small intestine the mucus layer is singular and does not contain any bacteria. The mucus layer of the large intestine is a bilayer. In the outer layer bacteria of the gut microbiome reside whereas the inner layer contains antimicrobial proteins and secretory immunoglobulin A to prevent direct microbiota contact with the colonic epithelium (Vancamelbeke & Vermeire, 2017).