Nkx2-1 - and Shh -lineage cells preferentially fate-map to complementary subdivisions of the posterior medial amygdala. (A) Schema of a caudal coronal section of an adult mouse brain showing the nuclei of the amygdala. The medial posterodorsal nucleus (MePD; red) is located lateral to the optic tract (opt; purple), and the medial posteroventral nucleus (MePV; green) is located ventrally and is bordered by the superficial layer of the medial nucleus (slMe; blue), which is a cell sparse fiber tract. (B,E,H) LacZ staining in postnatal day 22 (P22) Nkx2-1-Cre; TaumGFPbrains (n = 2) revealed that most recombined cells are found in the MePD (E, arrows), with fewer cells in the MePV (H, arrows). (C,F,I) Shh-producing cells revealed the opposite whereby more LacZ+ cells were observed in the MePV (I, arrows) of P22 ShhCre; TaumGFPbrains (n = 2) than the MePD (F, arrows). (D,G,J) A single dose of tamoxifen administered at E9.5 (TM E9.5: P22; tamoxifen at E9 and survival to P22) resulted in numerous LacZ+ cells in Gli1CreER(T2); TaumGFPbrains (n = 2). In this case, more recombined cells were observed in the MePD than MePV (G,J, arrows) of the posterior MeA. Abbreviations: BLA, basolateral amygdala nucleus; BMA, basomedial amygdala nucleus; Ce, central nucleus; HY, hypothalamus; LaDL, dorsolateral subdivision of the lateral amygdala nucleus; PIR, piriform cortex; PLCo, posterolateral cortical amygdala nucleus; PRh, perirhinal cortex; STR, striatum. Scale bar: 600 μm (B-D); 200 μm (E-J).