Cloning
Dolly, a Finn-Dorset ewe, was the first mammal to have been successfully cloned from an adult somatic cell. Dolly was formed by taking a cell from the udder of her 6-year old biological mother. Dolly's embryo was created by taking the cell and inserting it into a sheep ovum. It took 434 attempts before an embryo was successful. The embryo was then placed inside a female sheep that went through a normal pregnancy. She was cloned at the Roslin Institute in Scotland by British scientists Sir Ian Wilmut and Keith Campbell and lived there from her birth in 1996 until her death in 2003 when she was six. She was born on 5 July 1996 but not announced to the world until 22 February 1997. Her stuffed remains were placed at Edinburgh's Royal Museum, part of the National Museums of Scotland.
Hwang Woo-suk
In the late 1990s, the method that scientists used in cloning was somatic cell nuclear transfer, which is the same procedure that was used to create Dolly the sheep. This laboratory technique begins when an egg is taken from a donor and the nucleus is removed from the egg, creating an enucleated egg. A cell, which contains DNA, is then taken from the animal being cloned. The enucleated egg is then fused together with the nucleus of the cloning subject's cell using electricity. This creates an embryo, which is implanted into a surrogate mother through in vitro fertilization. If the procedure is successful, then the surrogate mother will give birth to a baby that is a clone of the cloning subject at the end of a normal gestation period. In 2014 researchers were reporting cloning success rates of seven to eight out of ten but in 1996 it took 277 attempts to create Dolly.