6-12 mo after secondary transplantation of young LSK48⁻34⁻E⁺150⁺ cells, regenerated donor LSK48⁻150⁺ cells were purified from selected positive secondary recipients (#1–#7) and injected at limiting dilutions (20, 40, or 100 cells) into tertiary recipients, as indicated in Fig. 3 and described in Materials and methods. Shown in the table are the proportion of tertiary transplanted animals in which continuing donor-derived hematopoiesis could be detected (>0.5% donor contribution to circulating Gr-1⁺SSC^hi granulocytes at 16-24 wk after transplant). Repopulation details of all positive tertiary recipients and the corresponding primary and secondary recipients are shown in Fig. 6.