Retina Ganglion Cells axons project from the eye to the contralateral optic tectum. We will present data illustrating the importance of axonal transport to regulate axon growth via an homeostatic. We have analyzed the effects of axonal transport genetic perturbation on retinotectal axon development, by deleting a kinesin I motor protein, Kif5aa andshowing that this disruption abolishes synaptic transmission in the retinotectal system. As a consequence we observe the development of excessive axonal branches caused by a compensatory upregulation of Neurotrophin-3 expression. This allowed us to unmask a general mechanism of homeostatic branching control by neurotrophin signaling. In the second part of the talk we will present new data on the importance of reelin signaling to control the precise lamination pattern of retina ganglion cell axons in the optic tectum. Using gene targeting approaches in zebrafish we demonstrate the importance of a reelin protein gradient in the neuropil, that controls precise synaptic lamination.