Thymic settling remains a regulated process after BMT. (A) Evans blue was measured in thymi or lungs after no treatment, lipopolysaccharide treatment, 1.5 Gy irradiation, or 9.5 Gy irradiation. Shown is the mean quantity ± SEM of Evans blue (micrograms) per organ weight (grams). *P < .05 compared with corresponding unirradiated controls. N = 4 to 6 per group. (B) Mice exposed to 0, 0.5, or 1.5 Gy of irradiation were inoculated with CD45.2 CCR7/CCR9 DKO BM cells plus CD45.1 WT BM at a 2:1 ratio (10⁶ total cells). Shown is the mean CD45.2 donor chimerism ± SEM of thymic DP cells after 3 weeks. *P < .05 compared with the control. N = 3 per group. (C) Top row: CD45.2 WT (left) or PSGL-1^−/− (right) BM cells (1.4 × 10⁷) were adoptively transferred into unirradiated CD45.1 WT hosts. Shown are representative plots of thymic DN3 cells 3 weeks after transfer. Bottom row: Mean CD45.2 chimerism ± SEM of BM granulocytes (left) and thymic DN3 cells (right). *P < .05 compared with the WT control. N = 5 to 10 per group. (D) Top row: Lethally irradiated BM chimeras were generated using CD45.2 WT (left) or CD45.2 PSGL-1^−/− BM (right) mixed with CD45.1 WT competitor cells at a 2:1 ratio (2 × 10⁶ total cells). Shown are representative plots of thymic DN3 cells 3 weeks after transplant. Bottom row: Mean CD45.2 chimerism ± SEM of BM granulocytes (left) and thymic DN3 cells (right). *P < .05 compared with the WT control. N = 5 to 10 per group.