Since Dolly, research into animal cloning has developed rapidly. Cattle, sheep, pigs, goats, horses, dogs and cats have all been cloned, as well as laboratory animals such as mice and rats.
Last month, the team involved in creating Dolly was reunited when they appeared on BBC Radio 4's 'Reunion' show.
Ian, Campbell, Bill Ritchie, Marjorie Ritchie and John Bracken, who is said to have named Dolly after popular country singer Dolly Parton, all took part.
Dolly started her life in a test tube before the embryo was transferred into a surrogate mother six days later. She was born on July 6, 1996, but the scientific development was not made public until the following year, to allow the results to be prepared.
Dolly went on to successfully produce six lambs, the first being Bonny in 1998. Dolly died in 2003.
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