lymph nodule

lymph nodule

n.

See lymph follicle.

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lymph nodule

Etymology: L, lympha, water, nodulus, small knot

any of the small densely packed spheric nodes or aggregations of lymph cells embedded in the reticular meshwork of the lymphatic system, mainly in the tonsils, spleen, and thymus.

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lymph

a transparent, usually slightly yellow, often opalescent liquid found within the lymphatic vessels, and collected from tissues in most parts of the body and returned to the blood via the lymphatic system. It is about 95% water; the remainder consists of plasma proteins and other chemical substances contained in the blood plasma, but in a slightly smaller percentage than in plasma. Its cellular component consists chiefly of lymphocytes.

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lymph duct

large vessels carrying lymph from smaller collecting vessels. Include thoracic duct, right lymphatic duct.

lymph heart

a muscular dilatation in a lymph vessel, capable of contraction and moving lymph along the vessel. Seen in embryos and lower vertebrates.

lymph node

any of the accumulations of lymphoid tissue organized as definite lymphoid organs along the course of lymphatic vessels, consisting of an outer cortical and an inner medullary part; they are the main source of lymphocytes of the peripheral blood and, as part of the reticuloendothelial system, serve as a defense mechanism by removing noxious agents, e.g. bacteria and toxins, and play a critical role in antibody formation. Sometimes called, incorrectly, lymph glands.

lymph node abscess

hard, usually cold swellings containing pus; secondary to primary lesion in node's drainage area; a feature of some chronic infections, e.g. tuberculosis, caseous lymphadenitis of sheep; specific nodes may cause specific syndromes, e.g. retropharyngeal nodes.

lymph node hyperplasia

increase in size due to increase in number of normal cells but with preservation of natal architecture.

lymph node hypoplasia

occurs in cattle and causes antenatal edema of the fetus, leading to dystocia in many cases. The calves are not viable.

lymph nodule

germinal centers in lymph nodes which produce lymphocytes. Called also lymphatic or lymphoid nodule.

periarteriolar lymph sheath (PALS)

the white pulp, heavily populated with T lymphocytes, that surrounds arteries in the spleen.

lymph tissue

see lymphoid tissue.