Fig. 8. Experiments examining the developmental relationship between GFP⁺FLK1⁺, GFP⁺FLK1^-, GFP^-FLK1⁺ and GFP^-FLK1^- populations isolated from differentiating Mixl1^GFP/w ES cells at day 2.8 (A), day 3 (B) and day 4 (C). At time points shown, a sample was removed from each culture and the EBs disaggregated. Cells were sorted into populations based on expression of GFP and FLK1 and recultured overnight. The following day, the sorted and unsorted populations, as well as EBs, from the continuing differentiation cultures were analysed for expression of GFP and FLK1.