Dolly was the first mammal cloned from an adult somatic cell.
The Finn Dorset sheep was created through somatic cell nuclear transfer at the Roslin Institute near Edinburgh. Scientists removed the nucleus from an egg cell and replaced it with the nucleus of an adult mammary-gland cell. An electrical pulse stimulated the reconstructed egg to begin developing, and the embryo was implanted into a surrogate ewe.
Dolly was born on 5 July 1996 and publicly announced in February 1997. She demonstrated that genetic material from a mature, differentiated cell could be reprogrammed to direct the development of an entire animal. This was a major result because many biologists had thought adult cells had lost that developmental potential.
Dolly was genetically almost identical to the nuclear donor, but not absolutely identical in every detail because mitochondria came from the egg cell. She lived until 2003 and was preserved for display at the National Museum of Scotland.