Sentinel Lymph Node Mapping

Lymph nodes are small round organs that are part of the body’s lymphatic system. The lymphatic system is a part of the immune system. It consists of a network of vessels and organs that contains lymph, a clear fluid that carries infection-fighting white blood cells as well as fluid and waste products from the body’s cells and tissues. In a person with cancer, lymph can also carry cancer cells that have broken off from the main tumor.

Anatomy of the lymphatic system, showing the lymph vessels and lymph organs, including lymph nodes, tonsils, thymus, spleen, and bone marrow. Top inset shows the structure of a lymph node and the lymph vessels, with arrows showing how lymph and immune cells called lymphocytes move into and out of the lymph node. Bottom inset shows a close-up of bone marrow.