Only MPPs yield myeloid thymic lineages, whereas CLPs generate lymphoid cells in the thymus. MPPs and CLPs were transferred into sublethally irradiated recipients as in Figure 2. At the indicated times, recipient thymuses were analyzed for donor-derived lineages. (A) Lineages of gated donor thymocytes 14 days after transplantation. Arrows in the top plots indicate gating hierarchy. The left column shows dendritic cells (CD11c⁺) versus T-committed progeny (Thy1.1⁺). The middle plots are gated to display myeloid progeny (Mac-1/Gr-1⁺), and the right plots show B220⁺ B cells. (B) The percentage of donor myeloid cells was computed as the percentage of total live cells that were CD45.1⁺Thy1.1⁻CD11c⁻Mac-1⁺. Data are taken from 2 of the time course experiments in Figure 2. Each symbol represents 1 mouse. Thymic myeloid chimerism is apparent from MPPs but not from CLPs over the time course analyzed. As determined by the Student t test, differences in myeloid chimerism were significant at days 14, 21, and 28 (P = .012, .007, and .023, respectively).