Figure 4.

Structure of the gastric crypt. (A) In normal gastric tissue, crypts are located within the lamina propria, a layer of connective tissue, that lines the submucosa. The gut-associated lymphoid tissue (GALT) is located within the submucosa and is made up of T and B lymphocytes that reactivate upon injury, inflammation or infection. (B) The crypt is split into four main zones, the base that contains mostly Lgr5+ stem cells, the neck, which acts as the transit-amplifying zone, the isthmus, which contains additional stem cells, and the pit, which contains mature mucus cells that fill the villi that extend into the stomach.