Newborn neurons in the ganglionic eminences are generated from RGs (neuroepithelial stem cells) in the VZ and from IPs in the SVZ. We found that radially organized cells resembling VZ in hMGEOs were enriched with SOX2 expressing cells, confirming their identity as neuroepithelial stem cells (Figure 2A). Outside VZ-like area there were SOX2+ progenitors delineating OSVZ-like area, but ISVZ-like area was distinguishable only at early stage (Figure 2A). In dissociated culture of early hMGEOs (day 21), we found that there were three sub-populations of neural progenitors: (1) SOX2+/NKX2-1-GFP- progenitors (19.76 ± 6.39%, n=10 hMGEOs, mean ± SD), (2) SOX2+/ NKX2-1-GFP+ progenitors (51.09 ± 7.93%, n=10 hMGEOs, mean ± SD), and (3) SOX2-/ NKX2-1-GFP+ progenitors (25.96 ± 5.34%, n=10 hMGEOs, mean ± SD), which may represent different developmental stages of MGE progenitors (Figure S1B) (Hansen et al., 2013). Indeed, the RG marker GFAP was only present in less-neuronally committed cells (Figure S1C). We found a marked trend of decrease of VZ-like area during hMGEOs development. While VZ-like area at early stages consisted of over 10 layers of stratified SOX2+ nucleus, the
