Altered thymopoiesis in p53cKO mice. (A) Thymic cellularity of Ctr and p53cKO mice at various ages. (B) Flow cytometry analysis of T-cell development in 10-week-old Ctr and p53cKO thymus: CD4/CD8 expression on total thymocytes (left); CD44/CD25 expression on DN thymocytes (gated on Lin⁻ cells) (middle left); CD177/CD25 expression on DN thymocytes (gated on Lin⁻ cells) (middle right). ETPs are defined as Lin⁻ CD177⁺CD44⁺CD25⁻; CD69/CD3 expression on total thymocytes (right). Numbers indicate the frequencies of the different subsets (mean ± SEM). (C) Fold change in the number of the indicated thymocyte subsets. For each time point, the values of Ctr mice were set as 1 (dashed line) and compared in relation to p53cKO mice. Graphs represent data from 2 to 3 experiments per time point (n = 6 to 8 mice per group; mean ± SEM). (D) Absolute number of splenic CD4⁺ and CD8⁺ T cells in Ctr and p53cKO mice at different time points. (E) Thymocyte cellularity of sublethally irradiated 6-week-old Ctr and p53cKO mice at the indicated time points posttreatment. (F) Fold change in the cellularity of the thymocyte subsets following sublethal total-body irradiation (SL-TBI). For each time point, the values of nonirradiated Ctr or p53cKO mice were set as 1 (dotted line) and to the ones obtained for SL-TBI Ctr and p53cKO thymus, respectively, at each time point. (G) Numbers of splenic CD4⁺ and CD8⁺ T cells in Ctr and p53cKO mice after SL-TBI. SL-TBI, sublethal total-body irradiation. *P < .05; **P < .01; ***P < .001.