Major defects in mRNA expression of putative inhibitory neuronal subtypes in the MePD of Nkx2-1 mutant mice. (A-F) mRNA expression in E18.5 control (A,C,E) or Nkx2-1 mutant (B,D,F) posterior MeA reveals significant defects in inhibitory neuronal subtypes, particularly in the MePD. (A,B) The mRNA expression of GAD67, a pan-inhibitory marker, is severely reduced in Nkx2-1 mutant mice (B) compared to controls (A). This is particularly evident in the MePD of the mutant (B, asterisk) as GAD67 mRNA expression appears stronger in the MePD in controls (A). (C,D) The Lhx6 mRNA expression in controls (C) is similar to that observed for GAD67, being notably stronger in the MePD than MePV. Although it is known that Nkx2-1 directly regulates Lhx6 expression, remnant Lhx6 mRNA expression was observed in the mutant posterior MeA, particularly around the MePD (D, asterisk). (E,F) The same was observed for Sst mRNA, whereby the expression in the control MePD (E) was significantly reduced in the mutant (F), although some remnant expression of Sst was observed in the MePD (F, asterisk). n = 4 for both control and Nkx2-1 mutant for each gene. Abbreviations: AMY, amygdala; CTX, cortex; HP, hippocampus; HY, hypothalamus; PIR, piriform cortex. Scale bar: A-F: 500 μm.