Gut-associated lymphoid tissue

The digestive tract's immune system is often referred to as gut-associated lymphoid tissue (GALT) and works to protect the body from invasion. GALT is an example of mucosa-associated lymphoid tissue.

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Function

About 70% of the body's immune system is found in the digestive tract. The GALT is made up of several types of lymphoid tissue that produce and store immune cells that carry out attacks and defend against pathogens.

New research indicates that GALT may continue to be a major site of HIV activity, even if drug treatment has reduced HIV count in the peripheral blood.^{[citation needed]}

Components

Lymphoid tissue in the gut is comprised of the following :

Tonsils (Waldeyer's ring)
Adenoids (Pharyngeal tonsils)
Peyer's patches
Lymphoid aggregates in the appendix and large intestine
Lymphoid tissue accumulating with age in the stomach
Small lymphoid aggregates in the oesophagus
Diffusely distributed lymphoid cells and plasma cells in the lamina propria of the gut

Additional images

v • d • e Anatomy of torso, digestive system: Gastrointestinal tract
Upper GI: to stomach	Mouth • Pharynx (nasopharynx, oropharynx, hypopharynx) • Esophagus • Crop
Upper GI: stomach	rugae - gastric pits - cardia/gland - fundus/gland - pylorus/gland - pyloric antrum - pyloric canal - greater curvature - lesser curvature - angular incisure
Lower GI: intestines	Small intestine: Duodenum (Suspensory muscle, Major duodenal papilla, Minor duodenal papilla) • Duodenojejunal flexure • Jejunum • Ileum • continuous (intestinal villus, crypts of Lieberkühn, circular folds) Junction: Vermiform appendix • Ileocecal valve Large intestine: Cecum • Colon (ascending colon, hepatic flexure, transverse colon, splenic flexure, descending colon, sigmoid colon) • continuous (taenia coli, haustra, epiploic appendix)
Lower GI: termination	Rectum: Houston valve • rectal ampulla • pectinate line Anal canal: anal valves • anal sinuses • anal columns • Hilton's white line Anus: Sphincter ani internus muscle • Sphincter ani externus muscle
Lower GI: lymph	GALT: Peyer's patches (M cells)

v • d • e Immune system: Lymphatic system (Lymph, Lymphocytes)
Primary	Bone marrow - Thymus (Hassall's corpuscles)
Secondary: Spleen (blood)	Hilum - Trabeculae - Red pulp (Cords of Billroth, Marginal zone) - White pulp (Periarteriolar lymphoid sheaths)
Secondary: Lymph nodes (extracellular fluid)	Subcapsular sinus - Paracortex - Lymph vessels - High endothelial venules
Secondary: MALT (mucosa)	GALT - Peyer's patches