By E18.5, the increased oligodendroglial specification from the dLGE is beginning to recover in Gsx2 mutants, with only slightly increased PDGFRα expression in the VZ/SVZ (D, compared to A) and no difference in Olig2-positive cells (E, compared to B) within the SVZ. Accordingly, Sp8 expression is also returning to the dLGE (F, compared to C). In contrast, Gsx1/2 double mutants continue to express highly increased levels of PDGFRα (G) and 01ig2 (H), while only few scattered Sp8- positive cells remain within the dLGE (I). The number of Olig2-positive cells as well as the area of PDGFRα- and Sp8-immunostained cells within the dLGE are quantified in J-L. Data represent the mean ±SEM. *p<0.01, as determined by a one-way ANOVA followed by a Tukey HSD post-hoc test. Scale bar: I = 100μΜ