Does the lymphatic system contain valves to prevent backward flow?
Valves are made of squamous cells and are present in vessels of the circulatory system, like lymph vessels, arteries and veins.
Valves work to prevent back flow.
When fluid flows in the wrong direction, it catches on the valve and pushes it back, closing off the vessel, forcing the fluid to turn around again. As it does so, the valve opens, no longer being pressured into a closed position, and normal circulation continues.