Fig 1. Model of an OPC and illustration of the proliferation/migration rules.

(a) Schematic drawing of an OPC where the cell center and the filipodia are visible. The cell is modeled by a 100 μm diameter sphere, represented by a dashed line drawn around the cell extensions. (b) A cell without overlap with other cells keeps moving with a constant velocity in the same direction. The direction of the motion changes only when the cell has overlaps with other cells. (c) The cell undergoes mitosis: a new cell is created and its center is placed at the distance R from the center of the first cell. (d) The two cells move in opposite direction in order to reduce the overlapping. After separation, they keep moving in the same direction, at a constant velocity.