Thymi of CCR7^−/−CCR9^−/− double deficient mice (DKO) are highly receptive for TSPs. Nonmanipulated WT and DKO recipient mice (CD45.2) were injected i.v. with congenic (CD45.1) WT lin⁻ BM-derived precursors. (A) WT and DKO total thymocyte numbers 21 d after injection of WT lin^– BM-derived precursors. (B) Analysis of WT and DKO recipient thymi 21 d after injection of WT lin⁻ BM-derived precursors. Representative plots delineating donor and recipient cells (left) and CD8α versus CD4 profiles of WT donor-derived cells (right). (C) Percentages and absolute numbers of WT donor cells within all thymocytes of WT and DKO recipients. Pooled data from five independent experiments are depicted. (D) Analysis of WT donor cells in spleen (top) and BM (bottom) of WT and DKO recipient mice 21 d after transfer of lin⁻ BM-derived progenitors. Pooled data from four independent experiments are depicted. (E) Analysis of WT and DKO thymi 21 d after injection of WT CLPs (CD45.1 and CD45.1/2). Representative plots of three independent experiments (left). Percentages and absolute numbers of donor cells within all thymocytes (right). (F) Analysis of WT donor cells in BM of WT and DKO recipient mice 21 d after transfer of CLPs. Data from three independent experiments. All recipient mice used in experiments shown in Fig. 1 were 4–6 wk old. Donor mice were 7–10 wk old. Each data point represents an individual mouse. Statistical analysis was performed using unpaired Student’s t test, where ns, P > 0.05; *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001.