A few days following thriving fertilization, an embryo gets to be a promptly dividing ball of cells referred to as a blastocyst. Juan Gaertner/Science Photo Library by way of Getty Pictures Promising assisted reproductive systems include ethical, legal and social challenges – a developmental biologist and a bioethicist examine IVF, https://single-bookmark.com/story18477723/facts-about-in-vitro-fertilization-revealed