Fig. 4: Oct4 is dispensable for CNCC induction but essential for ectomesenchyme specification.

(A) Side and front views of E9.5 Oct4^Flox/+; ActinCre^ER/+ and Oct4^Flox/Flox; ActinCre^ER/+ embryos treated with tamoxifen at E6.5. Asterisks indicate reduced FNM in Oct4^Flox/Flox; ActinCre^ER/+ embryos, black and yellow arrowheads point to BA1 and cephalic vesicle, respectively.

(B) Schematic representations of embryos shown in D. Asterisks indicate reduced FNM in Oct4^Flox/Flox; ActinCre^ER/+ embryos, black and yellow arrowheads point to BA1 and cephalic vesicle, respectively.

(C) Side views of whole mount RNA FISH against Wnt1 performed on E8.5 Oct4^Flox/+; ActinCre^ER/+ and Oct4^Flox/Flox; ActinCre^ER/+ embryos treated with tamoxifen at E6.5. Images are maximum projections. Dashed line indicates the NF limit.

(D) Immunofluorescence against AP2α, pH3 and Sox10 within transverse cross-sections of E9.5 Oct4^Flox/+; ActinCre^ER/+ and Oct4^Flox/Flox; ActinCre^ER/+ embryos treated with tamoxifen at E6.5. Cranial ganglia (CG) are indicated by yellow dashed lines.

(E) Quantification of proportions of AP2α⁺ cells, Sox10⁺/AP2α⁺ cells and pH3⁺/Sox10⁺/AP2α⁺ cells in CG (top) and FNM (bottom). Error bars indicated mean ± SD. Mann-Whitney non-parametric statistical test; *** p < 0.001.