Modeling Gastrulation in the Chick Embryo: Formation of the Primitive Streak
Figure 2
Simulation of differentiation in the early epiblast.
The embryo in these simulations contains (initially) 625 cells, i.e. 1 simulated cell corresponds to 16 cells in the real embryo. (A) Simulation showing that the embryo attains a stable circular shape, provided that the adhesion between cells is strong enough (J1,2>2J2,2). (B) To create the AP and AO we assign the AP cell type (red) to all cells whose centre-of-mass lies inside a circle of radius 77 voxels from the center of the embryo and the AO cell type (green) to the remaining cells. The AO (green cells) correspond to the AO in Fig. 1A (area where Wnt8c RNA is expressed). (C) Concentration field of the differentiation morphogen in the epiblast (according to Eq. 9). Gray-scale indicates concentration from 0 (black) to 1.5 (white). (D) Simulation of mesoderm (blue) differentiation. AP cells differentiate into mesoderm if the concentration of the differentiation morphogen in (C) is greater than 0.7. Blue cells form a Koller's Sickle, i.e. corresponding to the Wnt8c RNA expressing area in Fig. 1B. See Supplementary Materials Movie S2 for a movie of this process. See Simulation Details and Supplementary Materials Table S1 for the model architecture and parameter values. Simulations generated using the code in Supplementary Materials Code S1.