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MALT (Mucosa-Associated Lymphoid Tissue)

Protects mucous membranes of the respiratory, digestive, and genitourinary tracts and prevents pathogens from entering the body through mucosa.

Tonsils

Trap and destroy pathogens entering through mouth and nose; not fully encapsulated and contain crypts to trap bacteria and lymphoid follicles.

Peyer’s patches

Located in the ileum of small intestine; monitor gut bacteria and generate immune response, containing follicles similar to lymph nodes but lacking a capsule.

Appendix

Located at the junction of small and large intestine; contains lymphoid follicles and is believed to help maintain gut flora and immune defense.

Thymus

Organ responsible for the maturation of T lymphocytes and the production of thymic hormones that promote T cell development.

Cortex of Thymus

Dense region of the thymus filled with immature thymocytes.

Medulla of Thymus

Contains fewer cells and Hassall's corpuscles, which are concentric epithelial cell clusters.

Cisterna chyli

Dilated sac in the abdomen that collects lymph from the lower body and starts the thoracic duct.

Lymphedema

Swelling due to impaired lymph drainage.

Elephantiasis

Severe lymphedema caused by parasitic filarial worms.

High Endothelial Venules (HEVs)

Specialized venules in lymph nodes that allow lymphocytes to enter from blood.

Germinal centers

Sites within follicles where activated B cells proliferate and mutate to increase antibody affinity.

Reticular fibers

Fine collagen fibers providing structural support to lymphoid organs.