<P> The lymphatic circulation begins with blind ending ( closed at one end ) highly permeable superficial lymph capillaries , formed by endothelial cells with button - like junctions between them that allow fluid to pass through them when the interstitial pressure is sufficiently high . These button - like junctions consist of protein filaments like platelet endothelial cell adhesion molecule - 1 , or PECAM - 1 . A valve system in place here prevents the absorbed lymph from leaking back into the ISF . There is another system of semilunar ( semi = half ; lunar = related to the Moon ) valves that prevents back - flow of lymph along the lumen of the vessel . Lymph capillaries have many interconnections ( anastomoses ) between them and form a very fine network . </P>
<P> The lymphatic circulation begins with blind ending ( closed at one end ) highly permeable superficial lymph capillaries , formed by endothelial cells with button - like junctions between them that allow fluid to pass through them when the interstitial pressure is sufficiently high . These button - like junctions consist of protein filaments like platelet endothelial cell adhesion molecule - 1 , or PECAM - 1 . A valve system in place here prevents the absorbed lymph from leaking back into the ISF . There is another system of semilunar ( semi = half ; lunar = related to the Moon ) valves that prevents back - flow of lymph along the lumen of the vessel . Lymph capillaries have many interconnections ( anastomoses ) between them and form a very fine network . </P>
structure that prevents backflow of fluid in lymphatic vessels
structure that prevents backflow of fluid in lymphatic vessels
A valve system
A valve system