Physical constraints on early blastomere packings
Fig 2
Packing configurations and dynamics of 4-cell stage unconfined embryos.
A, Example of time evolution of cellular packings, showing how cell volume decreases by half upon division. B, Definition of possible topological arrangements at the 4-cell stage. C, Frequency of packing arrangements for slow and fast divisions (τD/τM = 0.1, 10, respectively), different contact angles θ and both ordered and random division rules (n = 103 simulation runs for each parameter set). D, Histogram of the time to reach the equilibrium tetrahedral configuration (n = 105 simulation runs for each condition). E, Frequency of packing configurations as the system relaxes to equilibrium (tE being the time to reach equilibrium) for both ordered (left) and random (right) divisions (n = 102 simulation runs for each condition). F, Top view (with cells) and cross section (without cells) showing the equipotential surface (orange tones) caused by three fixed cells on a fourth cell. G, Angular mean squared displacement (MSD) of a cell moving in the potential generated by three cells fixed in a triangle (n = 8 simulation runs), showing its diffusive nature (fit, gray line).