T-lineage reconstitution in DKO mice is independent of progenitor exit from circulation and intrathymic proliferation. (A) Analysis of thymi of WT and DKO recipient mice (CD45.2) 21 d after i.t. transfer of WT BM precursors (CD45.1/2). Representative plots of two independent experiments are depicted, n = 4. (B) Percentages and absolute numbers of donor cells within all thymocytes from experiments shown in A. (C) Analysis of BrdU incorporation in donor cells 14 and 21 d after i.v. injection of lin⁻ BM-derived precursors (CD45.1) into WT and DKO recipients (CD45.2). Density plots (left) and percentage of BrdU-positive cells within all donor cells (right). Recipient mice were 5 wk old. Donor mice were 8 wk old. Each data point represents one mouse. Data are representative of two independent experiments. Statistical analysis was performed using unpaired Student’s t test, where **, P ≤ 0.01.