Developmental progression of human T-lineage cells from Lin⁻ CD34⁺CD38^−/lo HSCs cultured on OP9-DL1 cells. (A) Flow cytometric analysis for the cell surface expression of CD34, CD5, CD1a, CD10, CD2, CD4, CD8, CD3, and CD7 from purified human CD34⁺CD38^−/lo HSCs before coculture with OP9-DL1 cells. (B-C) HSC/OP9-DL1 cocultures were harvested and analyzed by flow cytometry at the indicated time points for the expression of the markers as shown. The CD7 costaining with CD2 was performed with a different fluorophore-conjugated anti-CD7 mAb. Data are representative of at least 5 independent cocultures. Numbers in plots indicate percentage of cells within each quadrant.