Fig. 3. Early ventral patterning is never established in Smo^c/–;Foxg1^Cre mutants. (A-H) E10 coronal sections of the telencephalon stained by in situ hybridization with probes against Foxg1 (A,B), Pax6 (C,D), Nkx2.1 (E,F) and Gsh2 (G,H). The expression of Pax6 (C), which is normally restricted to the dorsal telencephalon (arrowhead at dorsal-ventral boundary), is found throughout the Smo^c/–;Foxg1^Cre mutant telencephalon (D). The wild-type ventral expression of Nkx2.1 (E) is absent from the mutant, with the exception of a small region of Nkx2.1 staining (F, arrow) that is of diencephalic origin (compare with arrow in B). Gsh2, which marks the intermediate telencephalic ventricular zone at this stage (G), is never observed in Smo^c/–;Foxg1^Cre mutants (H). Scale bar in A: 200 µm for A-H.