The tissues and organs that produce, store, and carry white blood cells that fight infections and other diseases. This system includes the bone marrow, spleen, thymus, lymph nodes, and lymphatic vessels (a network of thin tubes that carry lymph and white blood cells). Lymphatic vessels branch, like blood vessels, into all the tissues of the body.
Last updated: 2014-05-21
Source: The National Cancer Institute's Dictionary of Cancer Terms (http://www.cancer.gov/dictionary)