text: what is therapeutic cloning? how does it work?   therapeutic cloning (also known as somatic cell nuclear transfer, cell nuclear replacement, research cloning, and embryo cloning) involves taking an egg (or oocyte) from which the nucleus has been removed, and replacing that nucleus with dna from the cell of another organism. the result is a blastocyst (an early stage embryo with about 100 cells) with almost identical dna to the original organism.  the procedure is controversial, and this is reflected in the language used to describe the blastocyst created. some people believe it should not be called a blastocyst or embryo, since it has not been created by fertilisation, but others maintain that since, given the right conditions, it could still grow into a fetus and eventually a child, it doesn't seem misleading to call it an embryo. the aim of carrying out this procedure is to obtain stem cells that are genetically matched to the donor organism. for example, if a person with parkinson's disease donated their dna, then it should be theoretically possible to generate embryonic stem cells that could be used to treat their condition without being rejected by the patient's immune system.