Somatic cell nuclear transfer (SCNT) is a method of cloning an adult animal. It was used to make Dolly the sheep in 1996, the first mammal cloned from an adult body cell.Three animals are involved:
1. Animal A (the one to be cloned) gives a somatic (body) cell, for example an udder cell. Its nucleus is removed.
2. Animal B gives an egg cell (oocyte). The nucleus of the egg is removed, making an enucleated egg.
3. The nucleus from A is put into the enucleated egg. The two are fused using a small electric shock (electrofusion), which also stimulates the cell to start dividing.
4. The resulting embryo is grown in the lab and then implanted into animal C, a surrogate mother.
The offspring is a clone of animal A, because all of its nuclear DNA came from A. It is not a perfect copy: its mitochondrial DNA comes from the egg of animal B.SCNT is different from artificial twinning because it copies an adult whose features are already known, rather than an embryo whose features cannot yet be seen. The process is very inefficient: Dolly was the only lamb born from 277 attempts, so many eggs and surrogates are needed.
1. Animal A (the one to be cloned) gives a somatic (body) cell, for example an udder cell. Its nucleus is removed.
2. Animal B gives an egg cell (oocyte). The nucleus of the egg is removed, making an enucleated egg.
3. The nucleus from A is put into the enucleated egg. The two are fused using a small electric shock (electrofusion), which also stimulates the cell to start dividing.
4. The resulting embryo is grown in the lab and then implanted into animal C, a surrogate mother.
The offspring is a clone of animal A, because all of its nuclear DNA came from A. It is not a perfect copy: its mitochondrial DNA comes from the egg of animal B.SCNT is different from artificial twinning because it copies an adult whose features are already known, rather than an embryo whose features cannot yet be seen. The process is very inefficient: Dolly was the only lamb born from 277 attempts, so many eggs and surrogates are needed.