myeloblastListen to pronunciation(MY-eh-loh-blast)A type of immature white blood cell that forms in the bone marrow. Myeloblasts become mature white blood cells called granulocytes (neutrophils, basophils, and eosinophils).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#