Collective neuronal growth and self organization of axons.

I describe an assembly of neurons that synthesizes a chemorepellant molecule and transfers this molecule to the growth cones by axonal transport. From the growth cone, the repellant diffuses in nearby regions, achieving a certain concentration profile, delta, with a gradient. The growth cone migrates preferentially toward the regions of low delta. I show that this process self-consistently generates a profile of finite width, with a relatively sharp front of neuronal growth.