Fig. 3. Replating of embryonic cells into methylcellulose. (A) E7.5 cells per embryo were co-cultured with OP-9 cells in the presence of IL3, TPO, SCF, EPO and VEGF. On day 0, 1, 2 or 4, after treatment with trypsin, single cells were replated into methylcellulose with IL3, TPO, SCF, EPO and VEGF. Following 7 days of further culture, colonies formed were picked up. Cytospin preparations were made and were stained with Hemacolor. This experiment used a total of 20 E7.5 embryos (three MS-, four LS-, seven OB-, three EB-, three LB-stage embryos). (B) Data from a total of four embryos are shown. Two embryos were of ES stage and two embryos were of MS stage. nmE, neutrophil/macrophage/erythrocyte; mE, macrophage/erythrocyte; m, macrophage. (C) RT-PCR analysis for ßH1 and ß-major globin expression in individual hematopoietic colonies that were formed after contact with OP-9 cells for 3 days.