Collective cell migration occurs in many developmental contexts but a full understanding of this process has been hampered by a lack of quantitative analyses in 3D in vivo contexts. Using the zebrafish lateral line primordium as a model, Darren Gilmour and co-workers set out to tackle this problem (). The researchers develop a method to simultaneously live-label microtubules, centrosomes and nuclei, allowing them to map cell polarity and orientation across the migrating population. Using this method, they identify the transition between leader cells and followers within the collective and show that this transition is marked by changes in cell-cell adhesion; cadherin 2 is expressed across the tissue but is only assembled into adherens junctions (AJs) in the transition zone and further down the leader-follower axis. A tandem fluorescent protein timer-based approach reveals that AJs become progressively more stable along the leader-follower axis. Finally, they show that AJ assembly, but not maintenance, requires dynamic microtubules, revealing a key role for microtubules during leader-to-follower transitions within migrating collectives.
