How are animals cloned?
The technique used to clone whole animals, such as sheep, is referred to as reproductive cloning. In reproductive cloning, researchers remove a mature somatic cell, such as a skin cell or an udder cell, from an animal that they wish to copy. They then transfer the DNA of the donor animal’s somatic cell into an egg cell, or oocyte, that has had its own DNA-containing nucleus removed. Researchers can add the DNA from the somatic cell to the empty egg in two different ways. In the first method, they remove the DNA-containing nucleus of the somatic cell and inject it into the empty egg. In the second approach, they use an electrical current to fuse the entire somatic cell with the empty egg. In both processes, the egg is allowed to develop into an early-stage embryo in the test-tube and then is implanted into the womb of an adult female animal. Ultimately, the adult female gives birth to an animal that has the same genetic make up as the animal that donated the somatic cell. This young ani
