Generating a genetically identical copy of a cell or an organism

Dolly the Sheep

Dolly was cloned by Keith Campbell, Ian Wilmut and colleagues at the Roslin Institute, part of the University of Edinburgh, Scotland, and the biotechnology company PPL Therapeutics, based near Edinburgh. The cell used as the donor for the cloning of Dolly was taken from a mammary gland, and the production of a healthy clone, therefore, proved that a cell taken from a specific part of the body could recreate a whole individual.

She was created using the technique of somatic cell nuclear transfer, where the cell nucleus from an adult cell is transferred into an unfertilised 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 lived her entire life at the Roslin Institute in Midlothian. 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 2000. In late 2001, at the age of four, Dolly developed arthritis and

began to walk stiffly. This was treated with anti-inflammatory drugs.

Image: released into the public domain by its author, Squidonius at English Wikipedia.

The cloning process that produced Dolly