β-gal+ donor cell landing in brain (A), lung (B), liver (C), and spleen (D) after transplantation. Fresh marrow mononuclear cells, EMC, or EMC fractionated into ER-MP20+, ER-MP12+, and ER-MP20−12+ subpopulations were transplanted into B6/129F2 mice. Organs were removed at various time points and frozen tissue sections were prepared and studied for the presence of β-gal+ cells. Data are presented as the average number of β-gal+ cells per tissue section (y axis).