Conditional deletion of DLL4 or Notch ligands in Ocn⁺ cells impaired T lymphopoiesis. (A) OcnCreER^+/−;Dll4^Fl/Fl mutants and OcnCreER^+/−;Dll4^+/+ control littermates were injected with 2mg 4-OH-tamoxifen/15 g BW eight times over 4 wk to induce deletion of the DLL4 ligand. Mice were harvested immediately after 4 wk of deletion and bone marrow CLPs, thymic T cell progenitors, and peripheral blood mature T cells were enumerated by flow cytometry. Experiment was performed 3 times independently; n = 9–10 mice/group. Data show mean ± SEM. (B) OcnCreER^+/−;Mib1^Fl/Fl mutants and OcnCreER^+/−;Mib1^+/+ control littermates were injected with 2 mg 4-OH-tamoxifen/15 g BW 8 times over 4 wk to induce deletion of the Mib1 gene. Mice were harvested immediately after 4 wk of deletion and bone marrow CLPs, thymic T cell progenitors, and peripheral blood mature T cells were enumerated by flow cytometry. Experiment was performed twice independently; n = 6–8 mice/group. Data show mean ± SEM.