A computer simulation of geometrical configurations during cell division.

A process of cell division in the blastular wall of the starfish, Asterina pectinifera, was observed, and an attempt was made to model with a computer simulation the way in which cell number increases in such a tissue. Dividing cells at stages between the 2(11)-cell and the beginning of rotation were observed to shift these positions to the outer surface of the cell sheet by rounding up, after which they divide and slip back into the sheet as two columnar daughter cells. The change of a polygonal pattern of the blastular wall by cell division was simulated by making use of geometrical models of polygonal cells and the rule of the direction of cell division which was confirmed by observation. The simulation proves valid for describing changes of polygonal patterns of cell sheets including dividing cells.