Diffusion-weighted MRI tractography of radially coherent structures (arrow) indicative of radial glial scaffold in GW18 (sagittal, A) and GW19 (coronal, B) human fetal cortex. (C) Persistence of these radial structures (arrow) in a one-year-old patient with lissencephaly, indicative of aberrant radial glial development. R, right; A, anterior; S, superior. Copied from Takahashi et al, 2012 (A), Kolasinski et al, 2013 (B), and Kamiya et al, 2014 (C).