Fig. 6. Oligodendrocyte development is severely perturbed in the Smo^c/–;Foxg1^Cre mutant. (A-D) Coronal sections of an E12.5 wild-type (A,C) and Smo^c/–;Foxg1^Cre mutant (B,D) telencephalon. Expression of Olig2 and Pdgfra (A,C), both markers of oligodendrocyte precursors, was absent from the mutant telencephalon (B,D). Note that the anterior entopeduncular area, where markers of oligodendrocyte precursors are typically first seen, is not present in Smo^c/–;Foxg1^Cre mutants. (E,F) Representative low-power fields of cortical cultures derived from E16.5 wild-type (E) and mutant (F) cortex, stained four days later with O4, TuJ1 and DAPI. Smo^c/–;Foxg1^Cre mutant cultures show a 25-fold reduction in O4-positive oligodendrocyte precursors (G). Scale bars: 300 µm in A-D.