Loss of Nkx2.1 is dispensable for cortical interneuron identity of Isl1-derived precursors. (a) Isl1cre/+:tdTomato; Nkx2.1GFP/+ heterozygous and (b) Isl1cre/+:tdTomato; Nkx2.1GFP/GFP HD mice were sacrificed at E18.5 for comparison. Heterozygous mice showed tdTomato+ only (red), GFP+ only (green), and combined expressing (yellow) cells. GFP+ and tdTomato+ subcortical populations were mostly segregated in heterozygous mice. In contrast, HD mice showed a marked absence of GFP+ cortical cells with a shift to substantial overlap amongst GFP+/tdTomato+ (yellow) cells in basal ganglia. (c–h) E18.5 rostral (c,d), medial (e,f), and caudal (g,h) coronal sections. (i) Pie graphs show relative contribution of GFP+ only, tdTomato+ only and yellow cells within neocortex across conditions. For quantification, refer to text. One-way ANOVA P < 0.01 [rostral], P < 0.002 [medial], and P < 0.05 [caudal] was conducted across sample. N = 6 for pie graphs. Scale bars represent 200 μm (a,b) and 50 μm (c–h).