Axonal pathfinding. Detection of chemoattractants in the external environment by filopodia produces tension on the growth cone in particular directions. The growth cone will turn towards and grow along the dominant direction. If similar forces are exerted on opposite sides of the cone, the tension may be enough to split the cone into two, leading to the formation of daughter branches.
Graham and van Ooyen BMC Neuroscience 2006 7(Suppl 1):S9 doi:10.1186/1471-2202-7-S1-S9