Neural Plate Formation
The node of the mouse embryo (at the southern pole) forms from mesoderm. Subsequent mesoderm cells that pass through the node become notochord precursor cells, which move anteriorly along the bottom of the embryo. Like these cells, endoderm cells emerging from the primitive streak (at the posterior) also move anteriorly along the embryo. This embryonic endoderm collects in a “U” shape along the bottom and sides of the mouse embryo, and will in turn fold to form the gut tube. Mesoderm cells also move through the primitive streak, but in a lateral direction. In addition, presumptive neural ectoderm (green) are induced by notochord precursor cells and can be distinguished from the remaining ectoderm at the anterior of the embryo. The neural plate of the embryo expands giving rise to “head folds” on the dorsal side at the anterior of the embryo.