Figure 5.

Progenitor dynamics highlight immaturity of eFGF2-treated progenitors

(A) Cortical rosettes under Basal conditions recapitulated in vivo cortical development, showing apicobasal polarity (Ai and Aii), ZO1⁺ lumens (Aiii), PH3⁺ apical mitoses (white arrows, Aiii), and TBR2⁺ IPCs located basal to the lumen (Aiv). Rosette organization and TBR2⁺ IPCs were reduced after eFGF2 treatment and unaffected by MEKi. White circles highlight rosettes.

(B) At D35, IPCs were increased in Basal and MEKi conditions but were rare after eFGF2.

(C) No difference in Ki67⁺ cycling progenitors was observed.

(D) TBR2 quantification at D26 and D35 shows that eFGF2-treated cultures did not generate IPCs.

(E) MEKi generated larger rosettes, shown by increased ZO-1 lumen diameter (n = 3–5 independent experiments, one-way ANOVA with Dunnett's correction).

Data are mean ± SEM; ^∗p < 0.05, ^∗∗p < 0.01. Scale bar, 50 μm.