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thymus

(THY-mus)
An organ that is part of the lymphatic system, in which T lymphocytes grow and multiply. The thymus is in the chest behind the breastbone.
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Anatomy of the thymus gland; drawing shows the thymus gland in the upper chest under the breastbone. Also shown are the ribs, lungs, and heart.Enlarge this image in new window
Anatomy of the thymus gland. The thymus gland is a small organ that lies in the upper chest under the breastbone. It makes white blood cells, called lymphocytes, which protect the body against infections.
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