Fig. 1. Telencephalic loss of Shh reduces Nkx2.1 expression in progenitors of the MGE. Shown is the S-phase marker BrdU (red) and Nkx2.1 (green) immunolabeling on coronal 12 µm cryosections from E12.5 embryos. The outline in A indicates the bins of MGE used for quantification in G,H. Boxed areas in B and E are shown at higher magnification in C and F. (A-C) In NsCre(–):Shh^Fl/+ controls, roughly 90% of BrdU-labeled nuclei co-label with Nkx2.1. Over the entire MGE, this proportion falls to roughly 50% in the NsCre:Shh^fl/fl mutants, although effect was strongest in the dorsal MGE (t-test: *P<0.05, **P<0.01). Note, the bin 1 result in G and the bin2 result in H are not significant after adjustment for multiple comparisons. Scale bar: 200 µm in A,B,D,E; 50 µm in C,F.