Fig. 3. Lhx6 expression can rescue interneuron phenotypes in transplanted cells from Nkx2.1^-/- MGE^*. pLhx6-GFP was electroporated into the MGE-like region of E12.5 Nkx2.1^-/- slices, then after 1DIV the transfected regions were dissociated and transplanted into the cortex of neonatal pups. Shown are coronal sections through a P30 mouse that had received the transplantation into the cortical plate at P1. (A-H) Examples of co-labeling for GFP together with Kv3.1 and parvalbumin (PV; A-D), somatostatin (SST; E,F), and neuropeptide Y (NPY; G,H). In control experiments with pGFP vector, few cells expressing these markers are detected after transplantation of Nkx2.1^-/- MGE-like progenitors (see text and Table 1). (I,J) Transfected neurons (I, pGFP control; j, pLhx6-GFP) photographed at higher magnification to reveal dendritic spines. Insets show the boxed regions at higher magnification. (K) The frequency of heavily spiny neurons is significantly lower in the Nkx2.1^-/- MGE^* cells transfected with Lhx6 than in controls (41.9% versus 24.7%, n=3, ^*P<0.03). In addition, those Nkx2.1^-/- cells `rescued' for expression of PV or SST by Lhx6 are nearly all non- or sparsely spiny. These results suggest that Lhx6 can act downstream of Nkx2.1 to direct some aspects of both the neurochemical and morphological fates of MGE-derived cortical interneurons.