Gut-Associated Lymphoid Tissues

The intestine is the front line of the confrontation between pathogens and the immune system. However, it is also important to emphasize that we have a symbiotic relationship with innumerable bacteria in the intestine. In the gastrointestinal tract of mammals the lower intestine harbors around 1,000 12 species of anaerobic and aerobic bacteria, in densities up to 10 /mlinthe distal small intestine, the cecum, and the colon. A single layer of epithelial cells of the intestine protects the in...