As observed in developing cortex of human brain, SOX2+ RGs inside hCOs were organized into radial structures, with the apical surfaces marked by the expression of neural specific N-cadherin (Figure 3A). Newborn neurons generated from RGs expressed neuron-specific class III beta-tubulin (Tuj1), and were located on the basal side of the VZ-like area (Figure 3B). Cells in VZ-like area also expressed PAX6, another marker for RGs of the pallium, whereas NeuN, indicative of differentiated neurons, was observed outside of the VZ-like area (Figure 3C). The radially arranged GFAP+ fibers in VZ-area resembles RGs during corticogenesis in vivo (Figure 3D). We also examined the mitotic behavior of RGs by measuring the angle of the orientation relative to the apical surface of the hCOs. 75.35 ± 5.92% (n=4 hCOs, mean ± SD) adopted a vertical orientation, whereas only a minority of the RGs adopted horizontal orientations (Figure 3E). Furthermore, the staining with phospho-histone H3 revealed that dividing RGs were mostly located near the apical surface of VZ-like area (Figure 3F). Cleavage pattern of mitotic RGs showed that the majority of RGs (57.50
