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Lymph vessels are lined by endothelial cells, and have a thin layer of smooth muscle, and adventitia that binds the lymph vessels to the surrounding tissue. Lymph vessels are devoted to the propulsion of the lymph from the lymph capillaries, which are mainly concerned with the absorption of interstitial fluid from the tissues.
When an APC, such as a dendritic cell, binds a foreign antigen; it becomes activated and moves into the lymph nodes (sites for antigen sampling by T cells) via afferent lymphatic vessels. Naïve T cells in the circulation regularly move through the lymph nodes via HEV in order to scan the APC for foreign antigens.
Upon entering the lumen of a lymphatic capillary, the collected fluid is known as lymph. Each lymphatic capillary carries lymph into a lymphatic vessel, which in turn connects to a lymph node, a small bean-shaped gland that filters and monitors the lymphatic fluid for infections. [1] Lymph is ultimately returned to the venous circulation.
Lymph nodes are located at intervals along the lymphatic system. Several afferent lymph vessels bring in lymph, which percolates through the substance of the lymph node, and is then drained out by an efferent lymph vessel. Of the nearly 800 lymph nodes in the human body, about 300 are located in the head and neck. [23]
The lymph transport, in the thoracic duct, is mainly caused by the action of breathing, aided by the duct's smooth muscle and by internal valves which prevent the lymph from flowing back down again. There are also two valves at the junction of the duct with the left subclavian vein, to prevent the flow of venous blood into the duct.
The lymphatic vessels that link the lymph nodes are: The lymphatics of the head, face, neck, and meningeal lymphatic vessels – drain to the deep cervical lymph nodes; The jugular trunk; The subclavian lymph trunk; The thoracic duct; The lymphatics of the upper extremity; The right and left bronchomediastinal lymph trunks; The lymphatics of ...
Endothelium lines the inner wall of vessels, shown here. Microscopic view showing endothelium (at top) inside the heart. The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. This forms a barrier between vessels and tissues and control the flow of substances and fluid into and out of ...
A lymph duct is a great lymphatic vessel that empties lymph into one of the subclavian veins. There are two lymph ducts in the human body —the right lymphatic duct and the thoracic duct . The right lymphatic duct drains lymph from the right upper limb, right side of thorax and right halves of head and neck .