Dolly
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In 1997 a sheep named Dolly grabbed headlines all over the world. Researchers in Scotland had succeeded in cloning an adult sheep by taking the nucleus from on of its cells and placing it into an egg cell from a different sheep. The developing egg was then implanted into a third sheep. After a normal pregnancy, Dolly was born. Dolly was a clone of the first sheep; the DNA in her cells were identical to the DNA in the nucleus removed from the adult sheep. The process started with 277 eggs. From there, 29 embryos developed. Only Dolly survived.
Dolly appeared normal; she gave birth to six lambs. However, she lived only six years, a relatively short life span for a sheep. She suffered from arthritis and died from a respiratory infection, unusual conditions for a sheep of her age. Many scientists point to Dolly and evidence from cloned mice, cows, and other animals to show that clones are often not healthy or long-lived, though the reasons are not fully understood.
Dolly appeared normal; she gave birth to six lambs. However, she lived only six years, a relatively short life span for a sheep. She suffered from arthritis and died from a respiratory infection, unusual conditions for a sheep of her age. Many scientists point to Dolly and evidence from cloned mice, cows, and other animals to show that clones are often not healthy or long-lived, though the reasons are not fully understood.