Proceedings of the British Institute of Radiology

An 59Fe tracer technique for measuring the restoration of erythropoiesis by bone marrow cells following their transplantation into heavily irradiated rats was described. It was shown that this technique provides a measure of a biological function that is generally attributed to stem cells; namely the capacity of cells to maintain their own numbers as well as to provide a continuous supply of differentiating cells. The term “repopulating ability” has been used for this functional test of stem cells since the identity of the stem cells is still uncertain and because other techniques have been claimed as measuring these cells.