TL differentiation potential of CD45RA^hiCD7⁺ and CD45RA^hiLin^-CD10⁺ HPCs. (A) FTOC assay: sorted CD45RA^hiCD7⁺, CD45RA^hiLin^-CD10⁺, and bulk CD34⁺ cells were cultured for 4 weeks in NOD/SCID mouse fetal thymic lobes before cells were recovered and analyzed by FACS. Only CD45⁺ (R1) human cells were further analyzed. Percentages of positive cells are indicated; data are from 1 of 5 experiments. (B) Coculture with OP9-DL1 cells: CD34⁺ HPC populations were cultured for 2 or 4 weeks onto OP9-DL1 cells with SCF, FL, IL-2, IL-7, and IL-15, before FACS analysis. Percentages of positive cells are indicated; data are from 1 of 4 experiments.