(A) Representative immunostains for Collagen IV (ColIV) counterstained with hematoxylin, to depict non-vascularized (red outline) and vascularized (green outline) lesions from 37 Ptch+/− mouse cerebellar lesions sampled by serial sections at P14. (B) Boxplot showing statistically larger volume in P14 Ptch+/− lesions assigned as vascularized versus those assigned as non-vascularized, based on immunostaining serial sections of each lesion for ColIV. (C) Schematic illustrating the machinery required for Norrin activation of β-catenin (β-cat)/T-cell factor (TCF)-dependent transcription via the Fzd4 receptor and Lrp5 and Tspan12 co-receptors. (D) X-gal staining (blue) of sagittally sectioned cerebella from male Ndp-/y mice carrying an Ndp-lacZ KO allele, at the ages indicated. Bottom row, combined X-gal staining and immunohistochemistry (IHC, brown) for phospho-histone H3 (PH3), Pax6, and myelin basic protein (MBP). (E) Box plot of qRT-PCR analysis of Ndp expression in mouse Ptch+/− purified GNPs and MB lysate from symptomatic animals ranging in age from 3 to 10 months. (F) Box plot of NDP expression obtained by array profiling of human cerebella and two different cohorts (Boston, left; Toronto, right) of human MB samples, categorized by molecular subgroup. (G) Kaplan-Meier survival curve illustrating overall survival of Shh-MB patients with high versus low NDP expression. EGL, external granule layer; GNP, granule neuron progenitor; PCL, Purkinje cell layer; ML, molecular layer; WM, white matter; IGL, internal granule layer; CB, cerebellum; MB, medulloblastoma. Scale bars, 100 µm.