(Science: anatomy) small bean-shaped organ made up of a loose meshwork of reticular tissue in which are enmeshed large numbers of lymphocytes, macrophages and accessory cells located along the lymphatic system.
Recirculating lymphocytes leave the blood through the specialised high endothelial venules of the lymph node and pass through the node before being returned to the blood through the lymphatic system. Because the lymph nodes act as drainage points for tissue fluids, they are also regions in which foreign antigens present in the tissue fluid are most likely to begin to elicit an immune response. Nodes filter Out bacteria or cancer cells that may travel through the lymphatic system.
Synonym: lymph glands.