Characterization of brain organoids. (A to J) Immunostaining of formalin-fixed, paraffin-embedded sections, paraformaldehyde-fixed frozen sections of organoids, or paraformaldehyde-fixed whole-brain organoids with Tuj1/nestin (A), GFAP/MAP2 (B), vimentin/Tuj1 (C), Tau (HT7)/Cux2 (D), Tau-5 (E), calbindin (F), VGlut1 (G), TH (H), synaptophysin (I), and PSD95 (J). (D and F) Immunostaining of whole-brain organoids. Nuclei were counterstained with Hoechst 33342. Bars, 250 μm (A to C), 10 μm (G, H, and J), 50 μm (E and I), and 100 μm (D and F). (K) Comparison of the organization of a developing human brain with the organoids generated in this study. VZ, ventricular zone; iSVZ, inner subventricular zone; oSVZ, outer subventricular zone; IZ, intermediate zone; CP, cortical plate.