Figure 1.

Comparison of neurula stage expression of AP2α and other NC marker genes. (A) Whole-mount in situ hybridization with probes for AP2α, Slug, and Sox9 are shown in dorsal and lateral views. AP2α transcripts appear to extend more laterally than for the other two genes. This is shown more clearly in cross section in B, where the bracket indicates the Slug domain and the arrows point to the more extensive lateral AP2α. Note that under the conditions used here the epidermal expression of AP2α, which is considerably lower than for NC, is not apparent. The notochord is indicated by n. (Magnifications: A, ×7; B, ×42.)