(A) Schematic drawing of a stage 4 embryo. Dotted line indicates the presumptive neural plate. Red box indicates prospective FB explants used for in vitro studies.
(B–D) Sox2 and Sox3, in combination, were used as general presumptive neural markers. Each row represents consecutive sections from a single explant.
(B) Control stage 4 FB explants generated Sox2
+/3
+ but no
CdxC
+/CdxB
+ presumptive neural cells (
n = 24 explants).
(C) Stage 4 FB explants cultured in the presence of Wnt (˜150 ng/ml) and FGF (60 ng/ml) simultaneously generated
CdxC
+
/CdxB
+ presumptive caudal neural cells (
n = 26 explants).
(D) 4 FB explants cultivated in the presence of Wnt3A (˜150 ng/ml), RA (10 nM), and FGF (30 ng/ml) generated
CdxC
+
/CdxB
+ presumptive caudal neural cells (
n = 18 explants).
(E) 4 FB explants cultivated in the presence of Wnt3A (˜150 ng/ml) and RA (10 nM) did not generate
CdxC
+
/CdxB
+ presumptive caudal neural cells (
n =14 explants).