1996 – Scotland
‘A mammal can be cloned from adult tissues’
Clones are genetically identical individuals produced from the same parent by non-sexual reproduction.
Wilmut and his team at the Roslin Institute near Edinburgh, Scotland, took the nuclei of somatic cells from the tissues of mammary glands of a mature sheep. They took eggs from another sheep, removed their nuclei, which contain DNA, and fused the somatic nuclei with the gamete cells by passing electric pulses through them. The process replaced the DNA of the egg with the genetic material from the mammary tissue. The cloned eggs were placed in a culture dish where they grew into embryos. The researchers cloned 277 eggs, of which 29 grew into embryos. These were transplanted into 13 ewes, acting as surrogate mothers. Five months later one lamb was born. The lamb, Dolly, had no father and its genes came entirely from the udder of a ewe. Dolly the cloned sheep died in 2003.
The mammal cloning experiment has been repeated successfully on other species of mammals. These experiments show that cloning humans is possible, but it has major theological, ethical, moral and social implications.