Hematopoietic cell engraftment and T-cell differentiation in the thymus. The level of human CD45⁺ cells (A), CD4⁺CD8⁺ double-positive T cells (B), CD4⁺ single-positive T cells (C), CD8⁺ single-positive T cells (D), CD3⁺ T cells (E), and CD7⁺ T cells (F). *P < .05, **P < .01, ***P < .001 by Wilcoxon rank-sum test. ● represents experiment 1 females; ○, experiment 1 males; ■, experiment 2 females; and □, experiment 2 males. N = 5 to 7 per group.