<P> Dolly was born on 5 July 1996 and had three mothers (one provided the egg, another the DNA and a third carried the cloned embryo to term). She was created using the technique of somatic cell nuclear transfer, where the cell nucleus from an adult cell is transferred into an unfertilized oocyte (developing egg cell) that has had its cell nucleus removed . The hybrid cell is then stimulated to divide by an electric shock, and when it develops into a blastocyst it is implanted in a surrogate mother . Dolly was the first clone produced from a cell taken from an adult mammal . The production of Dolly showed that genes in the nucleus of such a mature differentiated somatic cell are still capable of reverting to an embryonic totipotent state, creating a cell that can then go on to develop into any part of an animal . Dolly's existence was announced to the public on 22 February 1997 . It gained much attention in the media . A commercial with Scottish scientists playing with sheep was aired on TV, and a special report in TIME Magazine featured Dolly the sheep . Science featured Dolly as the breakthrough of the year . Even though Dolly was not the first animal cloned, she received media attention because she was the first cloned from an adult cell . </P> <P> Dolly lived her entire life at the Roslin Institute in Edinburgh . There she was bred with a Welsh Mountain ram and produced six lambs in total . Her first lamb, named Bonnie, was born in April 1998 . The next year Dolly produced twin lambs Sally and Rosie, and she gave birth to triplets Lucy, Darcy and Cotton in the year after that . In late 2001, at the age of four, Dolly developed arthritis and began to walk stiffly . This was treated with anti-inflammatory drugs . </P> <P> On 14 February 2003, Dolly was euthanised because she had a progressive lung disease and severe arthritis . A Finn Dorset such as Dolly has a life expectancy of around 11 to 12 years, but Dolly lived 6.5 years . A post-mortem examination showed she had a form of lung cancer called ovine pulmonary adenocarcinoma, also known as Jaagsiekte, which is a fairly common disease of sheep and is caused by the retrovirus JSRV . Roslin scientists stated that they did not think there was a connection with Dolly being a clone, and that other sheep in the same flock had died of the same disease . Such lung diseases are a particular danger for sheep kept indoors, and Dolly had to sleep inside for security reasons . </P> <P> Some in the press speculated that a contributing factor to Dolly's death was that she could have been born with a genetic age of six years, the same age as the sheep from which she was cloned . One basis for this idea was the finding that Dolly's telomeres were short, which is typically a result of the aging process . The Roslin Institute stated that intensive health screening did not reveal any abnormalities in Dolly that could have come from advanced aging . </P>

How long did the cloned sheep dolly live