21.   But the embryos are destroyed, and opponents say the work is tantamount to murder.

22.   But the embryos are destroyed in the process, and opponents liken the science to murder.

23.   But the idea has raised ethical concerns because it would require starting to grow a human clone and then destroying the embryo to extract its stem cells.

24.   But the process destroys the embryo, ethically troubling many.

25.   But the research leaves some people deeply uneasy because the embryos are destroyed when the cells are extracted.

26.   But the working group of the American Association for the Advancement of Science recommends against allowing public funds to be spent in destroying embryos to obtain the stem cells.

27.   But there are ethical considerations in using embryonic stem cells because the cells are derived by destroying an embryo.

28.   But this research is controversial, because it requires that embryos be destroyed.

29.   Canine embryos have a large amount of fat in their cells that, when frozen, crack and destroy the embryo.

30.   Congress has forbidden the use of federal funds for any research in which a human embryo is destroyed.