Enhanced thymopoiesis in TGFβRII^lox/lox::Foxn1-Cre and recipient mice of HSCT early after irradiation. (A) Total thymic cellularity and (B) TEC cellularity in lethally irradiated recipients of T-cell–depleted bone marrow cells at different time points after transplantation (TEC cellularity of unconditioned mice that did not undergo transplantation was 0.42 × 10⁶ ± 0.07 × 10⁶ vs 0.41 × 10⁶ ± 0.07 × 10⁶, P > .05, for TGFβRII^lox/lox::Foxn1-Cre and TGFβRII^lox/lox, respectively). (C) The relative distribution of thymocytes according to CD4 and CD8 expression and (D) the absolute numbers of the 4 CD3⁻CD4⁻CD8⁻ subpopulations (DN1-4) were determined in TGFβRII^lox/lox::Foxn1-Cre and TGFβRII^lox/lox mice 2 weeks after lethal irradiation (950 cGy) and transfer of 10⁷ T cell–depleted bone marrow cells. Error bars represent SD, and percentages on plots in panel C are of total cells within gate.