Neurofilament staining (SMI-31) of Emx1-cKO and control brain cortices at P0. SMI-31 generally reacts broadly with thick and thin axons and some dendrites but not soma of neuron. Commissural neurons extended their axons down to ventricular zone and formed corpus callosum in control mice (a, c), while in Emx1-cKO mice (b, d) the axon trajectory was abnormal and axons (arrowheads) run obliquely within cortex, in addition a short corpus callosum was observed in Emx1-cKO mice (b, d)