slb prechordal plate progenitors migrate individually with increased motility and reduced cohesion when Mil function is compromised. (A-I) Time-lapse analysis and tracking of cell movement in migrating prechordal plate progenitors of WT embryos (A-C), slb embryos (D-F) and slb embryos injected with 4.3 ng mil-MO (G-I). Five cells were randomly chosen from each embryo, highlighted in different colours and tracked by merging each starting point to 0 (C,F,I). Twenty-five cells in total were accumulated from five independent experiments, to analyze for speed, persistence and coherence (J). In slb embryos, cell motility was significantly reduced (D-F). In slb embryos injected with mil-MO, the cells showed increased motility, and the cluster of cells appeared to be less coherent (G-I); the cells occasionally popped out from the cluster and travelled individually (H,I, asterisk). Such cell behaviour was never observed in WT embryos. (J) Summary of analysis of parameters: speed, persistence and coherence. Statistically significant differences are indicated (#P<0.05, ##P<0.005).