Supplementary Figure 1: Hes1-deficient progenitors show defective T cell development after intravenous injection and intrathymic injection.

(a) Photographs of Hes1^−/− or Hes1^+/+ embryos and flow cytometry analysis of fetal thymi (E15.5) (b) Flow cytometry of mixed irradiation chimeras made by intravenously injecting a mixture of either CD45.2⁺ Hes1^−/− or Hes1^+/+ littermate control FL (E15.5) and competitor CD45.1⁺ BM. Recipient mice were examined 8-10 weeks post reconstitution. (c) Flow cytometry of thymus from CD45.1⁺ recipient mice injected intrathymically with a mixture of CD45.2⁺ FL progenitors (Lin⁻Kit⁺Flt3⁺) sorted from Hes1^−/− or Hes1^+/+ littermate control embryos (15.5 dpc) and sorted CD45.1⁺ BM progenitors (Lin⁻Sca1⁺Kit⁺Flt3⁺) and intrathymically injected into sublethally irradiated CD45.1⁺ recipient mice. Recipient mice were examined 17 days post-injection.