Scientists say the event is important because it helps to demonstrate that Dolly is a healthy and fertile sheep, able to produce healthy offspring. Her baby lamb, called Bonnie, was the product of a normal mating with a Welsh mountain ram. The birth was said to be a normal delivery. Dolly's pregnancy was closely monitored Dolly grew from an egg cell which had its own nucleus removed and replaced with the nucleus of a body cell from a six-year old adult sheep. Cloning is one of the most controversial areas of contemporary science.
Supporters are keen to push back the boundaries as far as possible.
They hope that natural chemicals produced in the milk of cloned animals will be used in the widespread treatment of diseases such as haemophilia and the lung disease emphysema. There has been concern that cloned animals might be prematurely aged, or infertile, and this would hinder their use in producing such therapeutic proteins. Professor Graeme Bulfield, director of the Roslin Research Institute, said the birth was a milestone for science. The BBC is not responsible for the content of external internet sites.