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Overview of the Lymphatic System/Cell and Tissue Biology of the Lymph Node
Author(s) -
Bolender David,
Paulsen Douglas
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.388.1
Subject(s) - lymphatic system , lymph , lymph node , high endothelial venules , lymphatic vessel , lymphatic endothelium , pathology , lymph node stromal cell , thoracic duct , antigen , biology , anatomy , chemistry , medicine , immunology , cancer , genetics , metastasis
The lymphatic vascular system is a network of vessels (lymphatics) responsible for collecting tissue fluid from intercellular spaces and returning it to the venous system. Only the central nervous system lacks lymphatic vessels. Tissue fluid, originating as an ultrafiltrate of blood in capillary beds, enters the system through lymphatic capillaries and flows though a series of progressively larger vessels, the largest of which is the thoracic duct. Flow through the system is driven by compression of the surrounding tissues and directed by valves. At specific locations in the body, lymph vessels connect with encapsulated accumulations of lymphatic tissue known as lymph nodes. Lymph entering the nodes through afferent vessels percolates through sinuses allowing contact with macrophages and other antigen‐presenting cells. Foreign matter and cellular debris are filtered from the lymph and collect in the node. As reservoirs for tissue debris, metastatic cells, and infectious agents, lymph nodes improve the efficiency of interactions between reactive lymphocytes and these heralds of disease. Lymphoid nodules in the nodes' cortex contain abundant B‐lymphocytes that when activated form antibody‐secreting plasma cells. The nearby paracortical zone is a key point of contact between the blood and lymphatic vascular systems. Its high‐endothelial venules provide an entry point for T‐lymphocytes circulating in the blood and thus access to the reservoir of antigenic material in the node. Lymph nodes therefore play a critical role in lymphocyte activation for both humoral and cell‐mediated antigen disposal mechanisms. Filtrate exiting the node through the efferent vessels contains less antigenic material, but additional antibodies and activated lymphocytes.