Dolly was the first mammal to be cloned from an adult uddercell of a female adult sheep. Clone means making an animal from one single cell. Every cell has his pattern of gene and the pattern of an uddercell is not the same as from an embryonic cell. The pattern of the gene of the uddercell had to be changed into an embryonic cell from which Dolly was born. Before Dolly was created, there were already some cloned sheeps, but they were made from an embryonic cell, which is different from the way Dolly was made. On 14 February 2003, Dolly was euthanised because of a progressive lung disease and severe arthritis.
