Competitive repopulation. (A) Experimental schema. (B) Bone marrow cells from the indicated mice at 8 weeks of age were mixed at a ratio of 1 to 9 with competitor CD45.1 bone marrow cells from sex- and age-matched mice. These cells were transplanted into sex-matched, 6-week-old, lethally irradiated CD45.1 recipients. At the indicated time points, peripheral blood was assessed for ratios of CD45.2⁺ and CD45.1⁺ WBCs. (C) At 6 months of age, peripheral blood from mCG-PR^+/− × Rara^+/− recipients was assessed for ratios of CD45.2⁺ vs CD45.1⁺ cells in Gr1⁺, CD19⁺, and CD3⁺ compartments.