Hybrid Imaging of the Peripheral Lymphatic System

The lymphatic circulation is part of the peripheral circulation, linking blood circulation at its origins (the interstitial space) and at its final drainage point (the thoracic duct). The lymphatic system includes fluid (lymph), the lymphatic vessels, the lymph nodes (stations along the drainage route where fluid and cell exchange between blood and lymph occur), and other lymphoid tissue, particularly the spleen and bone marrow. The lymphatic system has a significant role in maintaining the balance of tissue fluid volume and an appropriate cellular chemical environment (the capillary plasma filtration process). An important role of the lymphatic circulation is the transport of the antigen and immune cells from peripheral tissues to lymph nodes. The interaction between lymphatic endothelial cells and leukocytes controls the immune cell migration and immune responses by regulating lymphatic flow and various secreted molecules such as chemokines and cytokines in tissue. Components of the lymphatic system include cells, vessels, and fluids. The lymphatic system is integrated with the hematopoietic and neurohormonal systems and can be divided into peripheral (from the interstitial space to and within the nearest lymph node) and central (efferent lymphatics, cisterna chyli, and thoracic duct, all lymphatic organs).