Structure, function, and molecular control of the skin lymphatic system.

The mechanisms of angiogenesis have been studied extensively over the past years. The focus, however, has been almost exclusively on blood vessels, whereas little effort has been directed toward understanding lymphangiogenesis and the role of lymphatic vessels in physiology and pathology. The lymphatic system, acting in concert with the blood vascular system, is of fundamental importance in maintaining tissue homeostasis, and disorders of the lymphatic system are common, often resulting in chronic, disabling conditions. This overview summarizes the most important aspects of the structure and function of the lymphatic system with emphasis on the skin lymphatic vasculature and the differences between blood and lymphatic vessels. Special attention has been given to the methods employed in research of the lymphatic system. Finally, we describe molecular mechanisms involved in the regulation of lymphangiogenesis. Vascular endothelial growth factor and vascular endothelial growth factor-C, expressed by distinct skin cell populations, play an important role in the molecular control of skin angiogenesis and lymphangiogenesis.