The thymus gland

The thymus gland is in the chest between the lungs. It makes white blood cells (T lymphocytes) which are part of the immune system and help fight infection.

The thymus gland is in the chest, between the lungs and behind the breastbone (sternum). It is just in front of, and above, the heart.

The thymus makes white blood cells called T lymphocytes (also called T cells). These are an important part of the body's immune system, which helps us to fight infection. The thymus produces all our T cells before we become teenagers. It gradually becomes less active and eventually gets smaller and is replaced by fat tissue. The thymus also produces a hormone called thymosin that helps make and develop T cells.

The diagram shows the network of lymph nodes throughout the body. There are nodes in the neck (cervical), armpit (axilla) and groin (inguinal). There are also lymph nodes in the chest and abdomen. The diagram shows the thymus gland at the top of the chest area, and the spleen, which is on the left side of the abdomen. The diagram also shows the diaphragm, which is the muscle that separates the chest from the abdomen.

See also

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