lymph vasculature

Unlike the blood vessels, the lymphatic vessels form a network of blunt-ended conduits with no direct connection to the blood vascular system. They collect and drain fluid and macromolecules from the interstitial spaces throughout the body, returning material that has left the circulation rather than carrying a closed circuit of their own. The vessels derive from a subpopulation of endothelial cells, and their walls are much thinner than those of the blood-carrying vessels, a difference consistent with the low pressures under which they operate. In descriptive anatomy they are usually classified as either superficial or deep according to their position relative to the investing fascia. Three subordinate structures are recorded beneath this entry.