(A) A scheme of the procedure. (B) Diagrams of developing CONCEPT organoids showing concentric zones of the anterior ectodermal progenitors. A summary of Figures 1, 2 and 7, Figure 1—figure supplements 1–3. (C) Morphology of cysts at day 2 showing the epithelial structure indicated by apical localization of the reporter TJ::GFP at the lumen. (D) Morphology of CONCEPT organoids at day 26. (E–G) Expression of telencephalon (Tel) marker Foxg1, neuroretinal (NR) markers Vsx2 and Pax6 in mouse eyes at E10-10.5. Rostral optic stalk (OS) connected the telencephalic vesicle to the optic cup. (H–O) FOXG1+ telencephalic progenitors, VSX2+ and/or PAX6+ retinal progenitors formed concentric zones in CONCEPT organoids. N>5 experiments. (P–W) In CONCEPT organoids, morphogens FGF8, BMP4, and BMP7 mRNA expression started at early stages and subsequently formed circular gradients. N>5 experiments. Scale bars, 100 µm (C, E, M, O, P, S, T), 200 µm (I, K), 500 µm (Q, U), 1 mm (D, H, J, L, N, R, V, W).