Fig. 3. Gli2 is required for expansion of the EGL and foliation at birth. Whole-mount analysis of WT and Gli2^–/– brains reveals a cerebellar phenotype. The mutant cerebellum (D) is smaller than that of the WT (A). Cresyl Violet staining of sagittal sections through medial WT (B) and mutant (E) brains shows reduced foliation in the mutant. Math1 expression indicates the presence of GCPs in the EGL of WT (C) and mutant (F) cerebella. High magnification image of PCNA labeling in the EGL demonstrates that the proliferative layer is thinner in mutants (H) compared with WT (G). Hematoxylin and eosin staining of Gli3^–/– brains shows that the EGL thickness is similar to WT (I). Region depicted in G,H is indicated in B,E. Anterior is to the left. EGL cell counts from three regions in WT and Gli2 mutant cerebellar sections were compared (J). In the mutant, regions I and III contain significantly fewer GCPs than WT at E18.5. Error bars indicate the s.d. Student's t-test was performed and showed a significant difference between WT and mutant in regions I and III (^*P<0.0001). Scale bar: 200 µm in B,C,E,F; 80 µm in G,H,I.