By E15.5, the tangential migration of immature cortical interneurons can be readily visualized by expression of Lhx6, Somatostatin (Sst), and EGFP (in Nkx2.1-Cre;CAG-EGFP brains) (Figures 2, S2D-S2F). By contrast, in Zfhx1b mutants (Nkx2.1-Cre), pallial expression of Lhx6, Sst, and EGFP was strongly attenuated (Figures 2, S2D’-S2F’). On the other hand, subpallial expression of these markers was increased in two locations: the striatum (asterisks Figures 2A-2C’, 2G-2I’, and S2D-S2F’) and a region contiguous with the caudoventral striatum, which we believe corresponds to the anlage of the central nucleus of the amygdala (labeled e, for ectopia; Figures 2E’, 2H’, S2D’; note that Figure S2T shows Dlx5 expression labeling the central nucleus of the amygdala, CeA). The ectopia in these regions also contained increased expression of Nkx2-1 and Sox6 (Figures 2D-2F’ and 2J-2L’). These genes are normally expressed in the subpallial projection neurons such as the globus pallidus, striatal interneurons and cortical interneurons (Sox6 only) (Azim et al., 2009; Batista-Brito et al., 2009).
