Fig. 2. (A-I) In situ hybridization of Scl. CD4⁺ and CD4^- cells were sorted from day 5 EBs and subjected to in situ hybridization. (A-D) CD4⁺ cells; (E-H) CD4^- cells; (I) E8.5 yolk sac. bi, blood islands; e, endoderm. (J) Kinetic analyses of FLK1 and SCL expression during EB development. In vitro differentiated ES cells (from day 2.75 to day 8) from wild-type R1 and three independent knock-in clones (1-4, 1-19, and 1-68) were subjected to FACS analyses for FLK1 and CD4 expression. Numbers in a given box indicate the percentage of cells that are FLK1⁺CD4^-, FLK1⁺CD4⁺ or FLK1^-CD4⁺.