大自然中的动物除了两性生殖外,一些动物如蜗牛、跳蚤等还具有孤雌生殖的本领。它们的卵子不受精就可直接发育成胚胎。目前,科学家正在尝试利用这种生殖方式生产大量胚胎干细胞,供医疗使用。干细胞是一种可以发育成各种组织器官的“万能细胞”,胚胎干细胞的活力最强大,但来源非常受限制。为了避免直接从正常人类胚胎获取干细胞的做法,科学家提出了利用克隆技术获得早期人类胚胎以提供干细胞的思路,但这种方法也导致了很大 In addition to the nature of animals in addition to amphiprotic animals, some animals such as snails, fleas also have the ability to parthenogenetic. Their eggs can not fertilize directly into embryos. At present, scientists are trying to use this way of reproduction to produce large numbers of embryonic stem cells for medical use. Stem cells are “all-purpose cells” that can develop into various tissues and organs. The stem cells are the most viable, but their sources are very limited. In order to avoid the direct acquisition of stem cells from normal human embryos, scientists have proposed the idea of ​​using cloning techniques to obtain early human embryos to provide stem cells. However, this method has also led to great