ectoderm

1.primitve ectoderm ;

英: blastodermic ectoderm ;

2.Bilateral oal thickenings of the surface ectoderm, called nasal placodes, then deelop on each side of the inferior part of the frontonasal prominence.

层表面呈双边卵圆形增厚形成鼻板，然后发展成为额鼻隆起下半部分。