Cerebral organoids were generated from hESCs (H9 and HUES8) and from human iPSCs using a modified protocol of Lancaster et al.40, described in the Supplementary Methods and in Supplementary Fig. 1. Eight-day hESC (H9) cerebral organoids were treated with the FGFR1 inhibitor, PD173074 (Abcam), by adding fresh media with 100 nM PD173074 or drug-free media every 2 days for 10 days. On day 18, the cerebral organoids were harvested, fixed, and processed for immunocytochemistry.
