Different marrow cell number requirements for the haemopoietic colony formation and the curve of the W/Wv anemia.

The lowest cell number in the normal marrow transplant, which allows the cure of W/Wv anemia was found to be between 10(4) and 10(5). This exceeds by several times the lowest cell number necessary for the haemopoietic colony formation. Therefore, either the colony forming cell is not the haemopoietic stem cell but rather its progeny, or this cell requires an aid from some other cells to exert is activity.