Cloning research. Researchers selecting embryos during bovine cloning. They are using light microscopes to help see the embryos and pick them up with pipettes. A cloned cow embryo is created by transferring nuclear material from a body (somatic) cell of a donor cow into an empty cow oocyte cell. The resulting cloned oocyte is cultured to the blastocyst embryo stage before being implanted into a foster cow for pregnancy. Clones of valuable domestic cows and the gaur (Bos frontalis), an endangered species related to the cow, have been created by this method. Clones of other animals, such as sheep and horses, are produced in the same way.