Bone marrow cells from Gata1^low mice engraft preferentially the extramedullary sites of the recipients. (A) Hematoxylin-eosin and CD45 immunostaining of liver sections from an untreated NOD/SCID female and from a NOD/SCID female that received a transplant of bone marrow cells from a Gata1^low/0 male. The presence of cells with the Gata1⁺ (220 bp, 2 alleles per cell) and Gata1^low (370 bp, one allele per cell) genotype in blood, bone marrow, spleen, and liver of representative NOD/SCID mice that received a transplant from either wild-type (C1-1) or Gata1^low (2 mice, TIP87 and TIP 66) mice is presented on the bottom. Results are representative of those obtained in 12 animals that underwent transplantation. Magnification ×20 in the panels and ×40 in the insets. (B) Frequency of cells expressing a lymphocyte (B220^pos or CD4^pos), granulomonocyte (Mac3^pos or Gr1^pos), and MK (CD41^pos/CD61^pos) phenotype in the blood and of those expressing a stem cell (Sca1^pos/CD117^pos), erythroid (CD71^pos/TER119^pos), and MK (CD41^pos/CD61^pos) phenotype in the marrow, spleen, and liver of a representative NOD/SCID mouse that received a transplant 2 months earlier of 10⁶ Gata1^low bone marrow cells. Similar results were observed in 6 additional mice that underwent transplantation. The presence of cells with the Gata1⁺ (220 bp) and Gata1^low (370 bp) genotype among the individual populations purified by sorting (> 90% pure by reanalysis) was assessed by PCR and presented on the right. Representative PCR analyses of cells purified from 3 representative recipients (each line is an individual mouse; A, B, or C). Representative isotype controls for the FACS analyses are presented in supplemental Figure 3.