Fig. 1. Model and elements of the computer simulation. (A) Polyhedral cells and polygonal surfaces are defined by vertices. (B) Reconnection of neighboring vertices. (C) Formation of a tetrahedral intercellular space at a vertex, corresponding to the blastocyst cavity. (D) Process of expanding the blastocyst cavity in the computer simulation. Volume of the intercellular space (V_Istd) is forced to increase linearly until t=500.