WBC and platelet reconstitution in chimeric mice. (A) Irradiated Tg(mpl) recipients were reconstituted with a 1:3 ratio of marrow cells from Tg(GFP) and Tg(mpl) donors. At 16 weeks after transplantation, the contribution of peripheral blood leukocytes and platelets coming from each of the engrafted donor marrow stem cells in chimeric mice was determined by flow cytometry; n = 15 mice. (B) A comparison of platelet counts and TPO levels in mice that received transplants that resulted in bone marrow chimeras (n = 15) and from mice that were reconstituted with only Tg(mpl) stem cells (n = 4). Means plus or minus SE are shown.