Fig. 5. Model of how slb cells with compromised Mil function can restore the net migration of prechordal plate progenitor cells. Normally, prechordal progenitors move persistently as a coherent cluster of cells. In slb embryos, the cells undergo reduced net migration due to a decrease in their cohesion and persistence. When injected with mil-MO, the slb cells are capable of undergoing directed migration as efficiently as WT cells, such that even under a circumstance in which coherence of migration is reduced, if cell motility is increased, it largely overrides the reduced directed migration. The length and size of arrows reflect the speed and efficiency of the migration of cells with respect to coherence and persistence.