the mature neuronal marker NEUN, which is present in the human forebrain only after 20 weeks of gestation11. The hCSs grew in size to more than 300 μm in diameter by 2 weeks of culture and reached up to 4 mm in diameter by 2.5 months (4.2 ± 0.3 mm, mean ± s.e.m., n = 16 hCSs from 4 differentiated hiPSC lines) (Fig. 1d).
