Mesoderm --- The middle germlayer in the early embryo; the source of cells that go on to make bones, muscles, connective tissue, heart, hematopoietic system, kidney, and other organs.
This suggests germlayer boundaries are less absolute than previously thought.
这表明胚层之间的界限并不是我们胰腺想想的那样严格。
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The middle embryonic germlayer lying between the ectoderm and the endoderm from which connective tissue muscle bone and the urogenital and circulatory systems develop.