In search of answers to these questions, we will take advantage of an ectopic testing system that we have developed in zebrafish, to study how Bmp, Fgf and Wnt signaling pathways shape the PPE.

• 至本世纪，争论的焦点为：在脊椎动物发育的原肠胚期是否存在一个特定的前基板区，并由此分化出头部周围感觉神经系统。