Stem cells from very early embryos are able to grow into any tissue in the body.

VOA: special.2009.04.07

Easiest to find them in embryos but sometimes they can be found in adult organisms as well.

它们在胚胎中最容易被找到,但有时在成人的机体中也能找到

耶鲁公开课 - 生物医学工程探索课程节选

stem cell research can go on without the ethical dilemma provided by killing embryos.

干细胞研究者可以免受由于杀死胚胎而带来的道德困境。

干细胞和伦理 - SpeakingMax英语口语达人

But opponents say stem cell experiments are wrong because human embryos are destroyed.

VOA: special.2009.04.07