Frizzled-3a and slit2 genetically interact to modulate midline axon crossing in the telencephalon

► Loss of zFzd3a perturbs formation of the forebrain commissures. ► Loss of zFzd3a causes expansion of the slit2 expression domain in the telencephalon. ► Loss of zFzd3a affects formation of the commissural plate. ► Knock down of Slit2 rescues the anterior commissure phenotype produced by loss of zFzda.