Fig. 8. Lowering Shh but not Gli levels partially rescues the Shh-P1 phenotype. Sagittal sections were analyzed for morphology. Removal of the downstream activator Gli does not affect cerebellar size (A) and does not show rescue of the mutant phenotype in double mutants (C), demonstrating that Gli is not the major activator of Shh signaling in the Shh-P1 cerebellum. When one allele of endogenous Shh was removed, a partial rescue of the Shh-P1 phenotype was observed (D). Although the cerebellum of Shh-P1; Shh^+/– was larger than the Gli^–/– (A), the IGL was not as thick or as irregular as the Shh-P1 IGL (B). Anterior is to the left. Scale bar: 320 µm.