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. Author manuscript; available in PMC: 2014 Jul 9.
Published in final edited form as: Curr Biol. 2010 Aug 5;20(17):1499–1510. doi: 10.1016/j.cub.2010.06.075

Figure 5. Simulations based on differential cortical tension support a two-step mechanism for endoderm invagination.

Figure 5

A: A model embryo constructed from contractile/viscoelastic elements. Different boundary colors indicate boundary-specific tension values. B: Starting and sample end geometries. C: Criteria used to specify passing geometries for Step 1 and Step 2 simulations of “wild type” ascidian embryos. Symbols are represented on Panel B. D,E: Summary view of how final geometries attained by simulation from initial Step 1 (D) and Step 2 (E) geometries vary as a function of tension ratios. Colored embryos correspond to tension ratios lying nearest the clouds of passing parameter sets shown in F,G. F,G: Position in tension ratio space of successful solutions shown as projections along the Mesecto_L/A (F) or Endo_L/A (G) axes. Values vary logarithmically along both axes and the central color legend applies to both panels. See Supplementary Modeling Procedures for details. Movies S6 and S7 show examples of successful Step 1 and 2 simulations. Figure S4 shows distributions of absolute tensions for Step 1 and 2 parameter space searches, and the results of parameter space searches with: (a) boundary-specific internal viscosities and (b) unconstrained variation of basal tensions.