求翻译 十分感谢

In 1968 Wilhelm His, a Swiss embryologist, made the controversial discovery that cells could migrate from the developing neural tube and form non-neural tissues . These observations identified an ectodermal origin for mesenchyme and skeletal tissues traditionally believed to only arise from mesoderm. We now know that these neural crest (NC) cells contribute many components of the vertebrate face, including smooth muscle, bone, teeth and cartilage. In time two distinct models for NC development emerged. The first declared that NC cells are pre-patterned, acquiring their developmental properties prior to their exit from the neuroepithelium .The second argued that ongoing interactions between the migrating NC cells and their surrounding tissues drive differentiation and morphogenesis . We now realize that there is a combination of initial developmental potential and continuous dynamic dialogue with flanking cells that together regulate NC developmental direction.