thymocyteListen to pronunciation(THY-moh-site)A type of white blood cell. Thymocytes are part of the immune system and develop from stem cells in the bone marrow. They help protect the body from infection and may help fight cancer. Also called T cell and T lymphocyte.Enlarge this image in new windowBlood cell development. A blood stem cell goes through several steps to become a red blood cell, platelet, or white blood cell. Search NCI's Dictionary of Cancer TermsStarts withContainsBrowse:ABCDEFGHIJKLMNOPQRSTUVWXYZ#