Dolly the sheep, the world's first cloned mammal, died at the Roslin Institute in Scotland yesterday. Her creators took the decision to "euthanase" six-year-old Dolly after they discovered signs of progressive lung disease.
"She had a lung infection and it was quite serious. It is something that happens in sheep," said Prof Ian Wilmut, of the Roslin Institute, who headed the team who created her in 1996.
"She had a detailed veterinary examination and they decided that because she wasn't going to recover, it was kinder to euthanase her," he added.
Now she has been promised to the National Museum of Scotland and will be put on display in Edinburgh in due course, a spokesman for the institute said.
Prof Wilmut said Dolly's death was not a setback for cloning technology and was not linked to the arthritis she developed at an unusually young age. He added the most likely explanation was that the infection had been transmitted from another animal in the barn.
"We have to await the results of the post-mortem," he added.
Some would argue that her age at her death - six years - and the age of the ewe her cell was taken from - also six years - means that she was really 12 years old when she died.
The birth of Dolly, in July 1996, made headlines around the world and sparked criticisms and fears that human cloning would not be far off.
At the time of Dolly's birth, Dr Harry Griffin, head of the Roslin Institute, defended her creation and said the research could help to produce new treatments for many diseases.
Dolly was named after the country and western singer Dolly Parton and gave birth to Bonnie in April 1998 and then to three more lambs in 1999.