Scientists believe therapeutic cloning ... the wait for transplant organs, therapies for a range of conditions could be pioneered. Because the tissue would originate from an embryo cloned from ...

zygotes or embryos. Moreover, precious animals of either sex (for example, endangered species and transgenic 11 animals) can be propagated by cloning irrespective of their fertility status.

The best source is the five-day-old embryo. Adult stem cells will differentiate into a narrower range of cell types. Bone marrow transplants are an example of adult stem cell transplant.