Figure 2.
GABAergic neurons generated from the POA2 region migrate caudally through the posterior amygdala stream (PAS). (A) Illustration of a whole embryonic brain at E13.5 showing the migratory paths (red and blue arrows) taken by the GABAergic neurons generated from the POA2 region, represented in dark red color. (B) Schematic of a horizontal section at the level of the plane shown in A. Neurons generated from the POA2 region express COUP-TFII and Nrp2 and migrate toward the HC, MeA, and caudal Cx via the PAS and CMS (red arrows). The red area represents the PAS. Neurons that downregulate COUP-TFII and therefore Nrp2 (blue arrows) detach from PAS and migrate across the striatum (Str, green color area) toward the cerebral cortex. (C) Schematic of a coronal section showing the different areas from which newly-generated GABAergic neurons migrate caudally. The POA is subdivided into POA1 and POA2 subregions while the Dg (also called AEP, cvMGE or pMGE by different authors) corresponds to the ventral region of the MGE. The POA2 progenitor domain (pPOA2) contains Dbx1+ progenitors, which produce GABAergic neurons migrating through the PAS (Hirata et al., 2009; Kanatani et al., 2015). The POA1 mantle (POA1m) is Nkx5.1+ but fail to generate neurons migrating caudally (Gelman et al., 2009; Kanatani et al., 2015). The Dg generates somatostatin (SST)-expressing neurons probably by also taking a migratory stream toward the caudal telencephalon (Puelles et al., 2016b). (C′) In situ hibridization showing Dbx1 expression in the POA2 region at E12.5.