Ocn⁺ cell–depleted animals had intact thymic function but impaired CLP homing ability. (A) 30,000 flow sorted bone marrow CLPs from diphtheria treated OcnCre^+/−;iDTR animals (Mut) or controls (Ctrl) were injected into the thymus of either OcnCre^+/−;iDTR DT treated (Mut) or control (Ctrl) animals. Injection of PBS served as mock controls. Thymic T progenitor and mature populations were assessed after 4 wk. Two independent experiments; n = 4–6 mice/group. Data show mean ± SEM. (B) CCR7, CCR9, and PSGL1 cell surface expression on CLP from Ocn⁺ cell–depleted or control mice was assessed by flow cytometry. Panels on the left show expression levels (indicated by fluorescent intensity on the y axis) and dot plots on the right show numbers of cells with positive expression. Minimum two independent experiments; n = 8–10 mice/group. Data show mean ± SEM. (C) CLPs from diphtheria-treated OcnCre;iDTR control and mutant mice were labeled with green and red fluorescent dyes, respectively, mixed in a 1:1 ratio and transplanted intravenously into congenic SJL recipients, and harvested 24 h after transplant. Equal number of CLPs harvested from CCR7^−/− mice was used as another control and competed with OcnCre;iDTR mutant CLPs in a similar manner. Donor-derived cells were enumerated from recipient thymi 24 h after transplant. Experiment was repeated with reciprocal dye to control for dye labeling efficiency. 2 independent experiments; n = 10 mice/experiment. Data show mean ± SEM.