The primitie mouth, or stomodeum, is a slight depression on the surface of the ectoderm.
原始的口（或口凹）是外胚的一的凹。
Bilateral oal thickenings of the surface ectoderm, called nasal placodes, then deelop on each side of the inferior part of the frontonasal prominence.
外胚呈双边卵圆形增厚形成鼻板，然后发展成为额鼻隆起的下半部分。
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Very early on in fetal development, the ectoderm which is the outer layer of the fertilized egg starts to develop a bit of a ridge that eventually becomes the neural tube.
在胎儿发育的早期，受精卵的外层，即外胚层，开始形成脊状突起，最后形成神经。
The jellyfish body is mainly composed of mesoglea, a jelly-like fluid sandwich between the outer ectoderm and the inner digestive cavity the endoderm.
水母的体主要由中间成，中间是一种果冻状的液体，夹在外外膜和内消化腔内膜之间。
The layer of cells, the endoderm, is thin, like the ectoderm, allowing nutrients to be directly absorbed into the surrounding cells.
细胞的内胚层很薄，像外胚层一样，可以让营养物直接被周围的细胞吸收。
The jellyfish absorbs oxygen through its ectoderm and can store it in the mesoglea.
水母通过外胚层吸收氧气，并将其储存在中层中。
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划词翻译
详细解释
的一
的凹
。
大揭秘 
。
体主要由中间
成，中间
