Fig. 8. Cell differentiation may be delayed at E11.5 in the absence of Sp8. (A-D) Double-immunohistochemical analysis presenting the expression of nestin (green) and ß-III-tubulin (Tuj1, red) as markers labeling undifferentiated neuronal progenitors and differentiating neurons, respectively. In Sp8 mutant embryos (E11.5), as indicated by the arrowheads in B and D, there are some cells outside of the ventricular zone that still express nestin but are devoid of Tuj1 signal. This suggests that these cells might correspond to neuronal progenitors that are not fully differentiated. C,D are at higher magnification than A,B.