In this con­text, blood-forming stem cells or blood stem cells. They are cells with litt­le or no dif­fe­ren­tia­ti­on. The various blood cells deve­lop from the­se parent cells. The­se stem cells are usual­ly found in the bone mar­row, espe­ci­al­ly of the ili­ac crest, the ster­num (breast­bo­ne), and thigh bone.