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 [small glands found along the vessels of the lymphatic system that filter out bacteria and other toxins, as well as cancer cells], 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.