Cell cycle dynamics controls fluidity of the developing mouse neuroepithelium

As organs are remodelled by morphogenetic changes and pattern formation during development, their material properties may change. To address whether and how this occurs in the mouse neural tube, we combined highly resolved mosaic analysis, biophysical modelling and perturbation experiments. We found that at early developmental stages the neuroepithelium surprisingly maintains both high junctional tension and high fluidity. This is achieved via a previously unrecognized mechanism in which interkinetic nuclear movements generate cell area dynamics that drive extensive cell rearrangements. Over time, the proliferation rate declines, effectively solidifying the tissue. Thus, unlike well-studied jamming transitions, the solidification we uncovered resembles a glass transition that depends on the dynamics of stresses generated by proliferation and differentiation. This new link between epithelial fluidity, interkinetic movements and cell cycle dynamics has implications for the precision of pattern formation and could be relevant to multiple developing tissues.