Fig. 5. Conserved aspects of AP-2 expression in amphioxus, lamprey, and gnathostomes. (A) Dorsal anterior view of similarly staged amphioxus (left panel), lamprey (middle panel) and axolotl (right panel) neurulae. In all three embryos, AP-2 is upregulated in the non-neural ectoderm and excluded from the neural plate. (B) Cross-sections through the anterior neural tube of amphioxus (left panel), lamprey (middle panel) and axolotl (right panel). All three embryos show AP-2 staining in the lateral walls of anterior neural tube (arrows) after neurulation. n, notocord.; np, neural plate; etc, non-neural ectoderm; nt, neural tube.