Thymocyte development in HIS and HIS-SGM3 mice. Human thymocyte development was analyzed 4, 8, and 12 weeks after human HSC transplantation by staining thymus-derived cells for the expression of human CD45, CD3, CD4, CD8, and FoxP3. (A) Total numbers of human CD45⁺CD3⁺ thymocytes at weeks 4, 8, and 12 in HIS and HIS-SGM3 mice are shown. (B) Frequencies of human CD4⁻CD8⁻ double-negative (DN), CD4⁺CD8⁺ double-positive (DP), CD4⁺ single-positive (CD4 SP), and CD8⁺ single-positive (CD8 SP) cells within the CD3⁺ thymocyte population at weeks 4, 8, and 12 are displayed. (C) The frequencies of single-positive CD3⁺CD4⁺FoxP3⁺ thymocytes at indicated time points in HIS and HIS-SGM3 mice are shown. (D) Original fluorescence-activated cell sorter plots showing FoxP3 expression in human CD4 SP thymocytes 12 weeks after HSC transplantation are depicted. Error bars indicate SEM.