1·The little tadpole about the size of a sesame seed is now made up of three layers: the ectoderm mesoderm and endoderm.
芝麻籽大小的小蝌蚪现在已经分成了三层：外胚层、中胚层和内胚层。
2·The little tadpole, about the size of a sesame seed, is now made up of three layers: the ectoderm, mesoderm and endoderm.
芝麻籽大小的小蝌蚪现在已经分成了三层：外胚层、中胚层和内胚层。
3·When an animal develops, embryos form three cellular or germ layers - ectoderm, endoderm and mesoderm - which then go on to form the body's organs and tissues.
当一个生物产生时，胚胎将形成三个胚层外胚层、内胚层和中胚层，然后再由这些胚层形成机体的组织和器官。
4·These epithelial elements arise embryologically from foregut endoderm in the process of bronchial tubular growth.
这些表皮细胞在胚胎学上把源于支气管生长过程中的前内脏叫内胚层。
5·They had never been found elsewhere but in the intestinal epithelium and this phenomenon supports the theory that EC cells are derived from endoderm.
上皮外未发现EC细胞，作者赞同肠道内分泌细胞的内胚层起源学说。