ABSTRACT
The lymphatic vascular system consists of a network of thin-walled capillaries that drain protein-rich lymph from the extracellular spaces within most organs. Lymphatic capillaries are lined by a continuous single-cell layer of overlapping endothelial cell lines. They lack a continuous basement membrane and pericyte coverage, and are thus highly permeable. The larger lymphatic vessels also contain a muscular and adventitial layer. Lymphatic vessels are absent from avascular tissues such as the epidermis and the nails. Unlike blood vessels, lymphatics are also absent from the cartilage, the brain, and the retina.
