Colon ('gut-associated lymphatic tissue' or GALT) (human)

Stain: Hematoxylin-PAS. Solitary lymphatic nodule in colon (see also Digestive System: Colon) A large amount of non-encapsulated diffuse lymphatic tissue or mucosa-associated lymphatic tissue (MALT) is located in the subepithelial lamina propria of the colon and called gut-associated lymphatic tissue (GALT). A secondary lymphatic nodule in the colon extends throughout the proper lamina (1). The nodule is similar to that found in a lymph node with germinal centre (2) and darker-stained mantle zone (3). The lumen is lined by a layer of columnar epithelial cells (4) with diapedesis of lymphocytes (-->). (5) short crypts with columnar absorptive epithelial cells and interspersed bluish red-stained goblet cells (-->, 6). A thin layer of lamina muscularis mucosae is visible (7). (8) submucosa layer composed as loose connective tissue.