In vitro differentiation potentials of c-kit⁺AA4.1⁺CD19⁻ (R2) and c-kit⁺AA4.1⁺CD19⁺ (R3) cells purified from 11-dpc livers.

Purified R2 and R3 cells were first expanded in vitro (ST2 + IL-7, IL-11, SCF) and then transferred to cultures under B-lymphoid (ST2 + IL-7), myeloid (SCF ± GM-CSF), and erythroid conditions (methlycellulose plus EPO, SCF). Positive wells were counted, photomicrographed, and analyzed by FACS at the end of the culture periods. Left column, light field photomicrographs of the cultures under B-lymphoid (× 20) and erythroid (× 4) conditions, and May-Grünwald-Giemsa photomicrographs from cytospin preparations of the myeloid cultures (× 20). The 2-color FACS analyses were performed as in Figure 2A, by using FITC anti-Thy1, anti-B220 and anti-CD11b, biotinylated anti-TER119, and Cy5 anti-CD19 mAbs.