To determine whether diminishment of VZ-like area is due to the differentiation of SOX2+ progenitors in this zone of the organoids, we next examined the distribution of DLX2-positive neuroblasts. In early stage hMGEOs, while SOX2 expression was enriched in VZ- and OSVZ-like area, DLX2 expression was largely excluded from VZ-like area (Figure 2E). After further development, more DLX2+ cells were distributed in VZ-like area with decrease of width of VZ-like area (Figure 2F). Moreover, ASCL1+ cells were present in VZ-like area at this stage (Figure S1D). Given the critical roles of DLX2 and ASCL1 in cell fate decision during subpallial VZ and SVZ development, these results suggest that as cells in SVZ-like area become neuronally committed during development of hMGEOs, cells in VZ-like area also undergo fate transition from neuroepithelial stem cells to more committed interneuron precursors.
