Hk2 deletion causes focal disruption of cerebellar development. Hk2 deletion caused focal disruption of cerebellar development as shown by comparison of cerebella with Hk2 deletion (top row) or with intact Hk2 (bottom row). Representative H & E-stained sections demonstrate focal disorganization of the CGNP lineage in hGFAP-cre;Hk2fl/fl mice (A), with regions of focal thickening (black arrowhead) and thinning (white arrowhead) and regions in which CGNPs failed to migrate over Purkinje cells (PC; black arrows) that were inwardly displaced. Yellow arrowhead, ectopic capillary in the EGL. By contrast, the EGL was evenly layered in an identical region of cerebellum of a Hk2fl/fl mouse without cre (B) and CGNPs completed migration across the PC layer (black arrows) to the IGL. (C) IHC for PC marker Calbindin (green) demonstrates a collection of PCs surrounded by the IGL in a hGFAP-cre;Hk2fl/fl mouse. Also note the presence of an ectopic capillary (yellow arrowhead), containing green autofluorescent red blood cells. (D) The IGL formed appropriately inside the PC layer in Hk2fl/fl mice without cre. (E,F) IHC for endothelial marker CD31 (red) demonstrates interruption of Hk2-deficient EGL by capillaries (yellow arrowheads). Nuclei are counterstained with DAPI. (G, H) IHC for PCNA (green) demonstrates the external, proliferative region of the EGL, while IHC for p27 (red) demonstrates the internal region of the EGL where CGNPs exit the cell cycle and begin to differentiate. The regular separation of layers within the EGL is disrupted in Hk2-deficient cerebella, with focal thinning (white arrowheads) and thickening of the proliferative PCNA+ layer (black arrowhead) and complementary change to the p27+ layer. All scale bars = 100 μm.