Dr Ian Wilmut, who created Dolly, the world's first cloned sheep, said it took 277 tries to get it right.
On June 21, the United Kingdom granted two patents for technologies that were used in creating the cloned sheep Dolly in 1997.
So far, scientists have successfully cloned sheep, cows, goats, pigs and mice.
Scientists have cloned sheep, cows, goats, pigs and mice, but their success rate is as low as one live birth in 100 attempts.
In Dolly's case, those cells were allowed to continue developing into an embryo that was then transferred to a ewe to produce a cloned sheep.
In the more than three years since scientists in Britain cloned the sheep Dolly, other researchers have successfully cloned sheep, cows, goats, pigs and mice.
The new study involves something similar to the cloning technique that led to the birth of Dolly, the famous cloned sheep that was born in July 1996.
When his daughter Mary's novel "Frankenstein, or the Modern Prometheus" was published in 1818, its readers were well primed to recognize the dreams and nightmares it reflected rather, perhaps, as we today might be expected to catch a reference to Dolly the cloned sheep.
He is also a little hard on the boomers, who have, after all, presided over economic growth, cloned sheep, become gay-friendly, spent a lot of time and money looking after their children and grandchildren, and who will not escape the current financial storm unscathed.
Also Wednesday, the researchers who cloned Dolly the sheep introduced five cloned pigs in the journal Nature.
Dr. Alan Colman, a member of the team that cloned Dolly the sheep -- the first cloned mammal -- in 1997, told CNN that within 20 years stem cell therapies could be used to treat degenerative diseases such as diabetes, congestive heart failure and Parkinson's disease.
In 1997, when Dolly the sheep became the first mammal to be cloned from an adult sheep, cloning a human entered the realm of possibility.
But the way soldiers are cloned in his galaxy far, far away bears little resemblance to the way sheep and cows are cloned on planet Earth.
Dolly the sheep -- the first cloned animal -- was created over 10 years ago, and the only previous claim of human embryo cloning by South Korean scientist Woo Suk Hwang in 2004, was discredited.
Finally, and most disturbingly to Dr Colman, half the cloned (and seemingly normal) cows and sheep that make it through to birth drop dead within three weeks.
Such nuclear transfer produced Dolly the sheep, the world's first cloned mammal, four years ago.
The centre became famous in 1996 for creating Dolly the sheep - the first mammal to be cloned from an adult cell.
The prospect of cloning a human moved from science fiction into the realm of possibility in 1997, when Dolly the sheep became the first mammal to be cloned from an adult.
Thirteen years ago, the world's first mammal to be cloned using DNA from an adult cell, Dolly the Sheep, was born in Edinburgh.
Dolly the sheep was the world's first mammal cloned from the DNA of an adult cell and was unveiled to the public in 1997.
The Roslin Institute's Dr. Ian Wilmut, who pioneered the technique that cloned Dolly from a single mammary cell from an adult sheep, said that while human cloning is theoretically possible, he saw no reason to do so.
It is a technique called nuclear transfer -- the same used to create Dolly the sheep -- and until Mitalipov's research there had been skepticism over whether a primate could be cloned in the same manner.
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