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 ± 10.60 %, n=2 hCOs, mean ± SD, 42 cells were measured) cleave vertical to the apical surface (Figure 3G). Abundant oblique cleavage (35.45 ± 7.71 %, mean ± SD) was also observed, but horizontal cleavage occurred infrequently (7.05 ± 2.90 %, mean ± SD) (Figure 3G). Thus, the mitotic behavior of RGs in hCOs resembles the trends previously observed in cerebral organoids and the ventricular zone of the fetal human brains (LaMonica et al., 2013; Lancaster et al., 2013).
