Lymph is the fluid that flows out from capillary walls to bathe the cells in the tissues of the body. It carried oxygen and other nutrients to those cells. It also contains white blood cells, which help fight infections. Waste products like carbon dioxide(CO2) can flow out of the cells and into lymph. Lymph fluid would build up and cause swelling if it wasn’t drained in some way, which is commonly called as lymphedema. That is the role of the lymph vessels. Lymph vessels draw up the lymph fluid from around the cells to send it towards the chest. Eventually, lymph collects into a large vessel that drains into a blood vessel near the heart.