Also called the lymphatic system, it is comprised of lymphatic vessels that run throughout the body (with the largest vessel being the thoracic duct, which collects a large portion of the body's lymph); lymph nodes, located in the neck, armpit, groin, and inside the center of the chest and abdomen; the tonsils and adenoids, which are collections of
lymphoid tissue similar to lymph nodes; and the spleen and thymus, which are lymphoid organs.