Aulehla, A.; Erzberger, A.; Stokkermans, A.; Zhao, M. L.; Rombouts, J.

Robust development depends on maintaining correct proportions as overall size varies. What controls and limits this ability to scale remains poorly understood in part due to the complex interplay between mechanical and biochemical factors within developing embryos. Using confinement of dissociated embryonic presomitic mesoderm cells, combined with imaging and chemical perturbations, we identified aggregation as the initial event in de novo anterior-posterior axis patterning. Using a continuum model solely based on cell-cell attraction, we quantitatively map out how the time available for aggregation-driven patterning limits the system size over which scaling can be maintained: Small systems allow for rapid and robust pattern scaling whereas coarsening dynamics substantially delay the appearance of a scaled pattern in large systems. Our experiments quantitatively confirm these predicted scaling regimes. Together, our results suggest a developmental time-size tradeoff on the scaling of aggregation-driven patterns.