The lymph is a biological fluid produced as the affluent of interstitial fluid from most parenchymal organs. The lymphatic system is a system of thin tubes and lymph nodes that run throughout the body.A number of specialised tissues are important for the proper functioning of the immune system. This phenomenon is applied to find sentinel lymph nodes in cancer patients. A significant fraction of the total immune cells in the body are located in several hundred lymph nodes.Some lymphocytes migrate to the thymus and become T cells that circulate in the blood and are associated with the lymph nodes and spleen. The lymphatic system helps protect us from infection and disease. It is part of the body's immune system. Lymph fluid passes through lymph nodes. The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the circulatory system and the immune system. It is made up of a large network of lymphatic vessels, lymphatic or lymphoid organs, and lymphoid tissues. The primary function of the lymphatic system is to transport lymph, a fluid containing infection-fighting white blood cells, throughout the body.Lymph is clear or white fluid that travels through vessels, moves within tissues and work to keep all the parts of the body clean. The lymph capillaries drain into still larger collecting vessels.