Electron micrographs of breaks in the glia limitans. Electron micrographs are from nestin-Cre/DG-null cerebellum and littermate control at P7. In panels A 1 and B 1 ( duplicates of panels A and B), a subset of Bergmann glia processes are shaded in green while selected GCs are colored in red and GCs undergoing mitosis are painted in blue. Panels C and D are higher magnification images of the regions of interest indicated by arrows in panels A, A 1, B, and B 1. A continuous basal lamina (arrowheads) lines either side of this fissure in a control P7 cerebellum (C). A DG-null littermate (D) displays a region containing abnormally organized radial glia processes and a largely absent basal lamina. Cells have migrated into the fissure, leaving a fragment of the glia limitans (arrowheads) buried beneath heterotopic cells. Scale bar: 10 μm (A and B); 0.5 μm (C and D).