Fig. 6. Analysis of markers for ventrolateral mesoderm and neurectoderm in sqt^-/-; cyc^+/+ and sqt^-/-; cyc^+/- embryos. The genes, genotypes and stages analyzed are shown. Fusion of paraxial and adaxial myod expression domains is apparent in sqt^-/-; cyc^+/- embryos (C,F). In wild-type, sqt^-/-; cyc^+/+ and sqt^-/-; cyc^+/- embryos, spt (G-L), tbx6 (M-O) and vox (P-R) are each strongly expressed around the ventrolateral margin. tbx6 and vox are normally excluded from the dorsal margin, and this region of exclusion is expanded in sqt^-/-; cyc^+/- embryos (O,R). spt expression in the prechordal plate (J, arrow), is reduced in sqt^-/-; cyc^+/+ (arrow) and absent in sqt^-/-; cyc^+/- embryos, while marginal expression is excluded from a larger dorsal sector in sqt^-/-; cyc^+/- embryos (I,L) than in sqt^-/-; cyc^+/+ or wild-type embryos. ntl is also reduced dorsally in sqt^-/-; cyc^+/+ (T) and absent dorsally in sqt^-/-; cyc^+/- (U) embryos. (V-X) Expression of neural marker cyp26. Lateral views, dorsal towards the right. Arrow indicates marginal domain of cyp26 expression, arrowheads indicate vegetal extent of neural domain. The neural expression is shifted slightly towards the margin in sqt^-/-; cyc^+/+ embryos (W), and more dramatically in sqt^-/-; cyc^+/- embryos (X). In X, the dorsal marginal domain of cyp26 expression is located at a more animal position than the ventrolateral marginal domain, apparently because of abnormal morphogenetic movements of dorsal cells in sqt^-/-; cyc^+/- embryos. Dorsal views with anterior towards the left (A-F), animal views with dorsal to the right (G-I,P-R,S-U), dorsal views with animal pole upwards (J-O) and lateral views with animal pole upwards (V-X). The genotypes of all embryos shown were determined by PCR after photography.

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