Kinetics of blast and hematopoietic colony rescue from Scl^-/- derived populations. (A) Kinetics of blast colony development in Scl^+/+ EBs (▦ , 2° EBs; ▪, BLASTS). Numbers below the graph indicate the day of differentiation. Data are presented as mean number of colonies from 3 dishes. Bars, where visible, represent SEM. (B) Blast colony potential of FLK-1⁺ cells from day 3.5 Scl^+/+ EBs (+/+, 3.5) and FLK-1⁺ cells from day 3.5, 4, 5, and 6 Scl^-/- EBs (-/-, 3.5/4/5/6). Colony-forming potential was measured in the various FLK-1⁺ populations prior to (- virus) and following infection with SCLVPCs (+ virus). Colony numbers are presented per 10⁵ input cells. Data are presented as mean number of colonies from 3 dishes. Bars, where visible, represent SEM. (C) Hematopoietic progenitor potential of FLK-1⁺ cells from day 3.5 Scl^+/+ EBs (+/+, 3.5) and FLK-1⁺ cells from day 4, 5, and 6 Scl^-/- EBs (-/-, 4/5/6). Colony-forming potential was measured prior to (- virus) and following infection with SCLVPCs (+ virus). □ indicates ERY/P; ▪, MAC; ▨, E/MAC; and ▦, MIX. Colony numbers are represented per 10⁵ input cells. Data are presented as mean number of colonies from 3 dishes. Bars, where visible, represent SEM. (D) Expression analyses of the presorted (P), FLK-1^- (-) and FLK-1⁺ (+) fractions from day 3.5 Scl^+/+ EBs (+/+) and from the different stage Scl^-/- EBs (-/-). Boxes highlight Brachyury expression in FLK-1⁺ fractions from Scl^+/+ and Scl^-/- EBs at the indicated time points (in days) shown below the figure.