We can see the early signs of ear development Start with the thickening of the outer layer of the embryo, this layer is called the ectoderm.

大家知道，耳朵发育的早期特征,是胚胎外层膜的增厚，这层膜也叫外胚层。

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And shortly thereafter this thickening of the outer surface is dimpling in, its invaginating.

增厚的外胚层很快就,向内凹陷。

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