Fig. 1. The size of the dorsal telencephalon is reduced in Shh-CKO and Smo-CKO embryos. Dorsal views of wild-type (A), Shh-CKO mutant (A') and Smo-CKO (A'') mutant brains at E18.5. The appearance of the mutant brains was grossly normal. Coronal sections of wild-type (B), Shh-CKO (B') and Smo-CKO (B'') telencephalons at E18.5 were stained with HE. These panels illustrated that the size of the dorsal telencephalon was slightly, but significantly reduced in the mutants (see Table 1). Note that the thickness of the mutant cortices is slightly thinner than that of the wild-type cortex (asterisk). The angle of the lower extension of the lateral ventricle (arrow in B) is almost perpendicular in wild type, while that of the mutants is medially inclined (arrow in B',B''). By contrast, the ventral parts were not apparently affected. In situ hybridization of Smo on E18.5 wild-type (C) and Smo-CKO mutant (C') embryo brains. The expression of Smo was undetected specifically in the dorsal telencephalon in the mutant brain. Scale bar: 1 mm in A-A''; 200 µm in B-B''; 100 µm in C,C'.