Critical roles of FLT3L and IL-7 but not TSLP in adult thymopoiesis. (A) Mean (SD) thymic cellularity, (B) FACS profiles of DN development, and mean (SD) numbers of (C) DN cells and (D) CD4 and CD8 SP and DP thymocytes of 9- to 11-week-old WT, Flt3l^−/−Il7^−/− and Flt3l^−/−Il7r^−/− mice. Numbers in FACS profiles show the mean percentages (of total thymocytes) of cells within the indicated gates. Data are from 5 WT, 6 to 13 Flt3l^−/−Il7^−/− and 4-10 Flt3l^−/−Il7r^−/− mice from at least 2 separate litters. (E,F) Mean (SD) numbers of (E) DN cells and (F) CD4 and CD8 SP and DP thymocytes of 9- to 11 week-old littermate Flt3l^−/− and Flt3l^−/−Tpte2^−/− mice. Data are from 8 littermate Flt3l^−/− and 10 Flt3l^−/−Tpte2^−/− mice from 2 separate litters. All groups were investigated for statistical differences by Student t test (*P < .05, **P < .01). Unless otherwise indicated, differences were nonsignificant.