Lymph nodes comprise the locations outside the primary immune organs where some immune cells mature and develop.

The tonsils and spleen are also an example of lymph nodes, however, they are often given their common names for easy identification.

The lymph vessels form the circulatory network that moves the lymphatic fluid around the body. One way valves in the vessels keep the fluid moving in one direction. Pumping of the fluid is achieved through the skeletal muscle contraction that compresses the vessels that lie within them.