Any of us who have seen a friend or relative suffer from MS for 20 or 30 years or from Alzheimer's disease or any similar disease would say it is not an unreasonable ethical trade-off to use embryos, which in five years time would die anyway and which are often flushed down the drain. I like to think of it in terms of organ donation. Embryos belongs to the parents concerned. It is not unreasonable, if it is the wish of parents, to donate embryos just as they would donate the organs of their nearest and dearest to restore to life somebody else who has been deprived of life.