At P4, the majority of IGF-1R knocked-down cells remained arrested at the VZ/SVZ/IZ, exhibited a multipolar morphology, and clustered forming highly heterotrophic arrays (Fig. 7, right); in contrast, control cells migrated normally and exhibited a normal branched morphology of apical neurites and a tailing axon (Fig. 7, left).Figure 7IGF-1R suppressed neurons remain as multipolar cells even at P4. Cells arrested in the VZ/SVZ/IZ in brains electroporated with the shRNA-IGF-1R and analyzed at P4 are mainly multipolar cells arranged in heterotopic groups (right). Control cells in layers II-IV show normal differentiation with a ramified dendrite (arrowhead) and a trailing axon (left). Calibration bar = 10 μm.