Structure of Lymphatic Capillaries. Lymph or lymphatic capillaries are tiny thin-walled vessels, closed at one end and located in the spaces between cells throughout the body. These are particularly dense within connective tissue. Lymphatic capillaries are slightly larger in diameter than blood capillaries and contain flap-like “minivalves”…
Upon entering the lumen of a lymphatic capillary, the collected fluid and associated cells (notably white blood cells) is known as lymph. Each lymphatic capillary carries lymph into a lymphatic vessel, which in turn connects to a lymph node. Lymph is ultimately returned to the venous circulation .
Because lymphatic capillaries have a closed end and minivalves normally prevent backflow into tissues, the pressure of lymph becomes higher as more lymph is collected from the tissues, which sends the lymph fluid forward. Multiple capillaries converge in collecting vessels, where the internal valves and smooth muscle start to appear.