HOW DOES SCNT CLONING WORK?
A cell in an early embryo has something akin to a superpower. It can transform into any part of the organism, a skin cell perhaps, a muscle cell, a nerve cell or a blood cell. Before Dolly, everyone assumed that in mammals this process of specialisation, so-called ‘differentiation’, was irreversible. Dolly proved otherwise. Scientists start with an egg cell . The nucleus (the part of the cell that contains the majority of the genetic material) is removed from the egg cell . A single differentiated cell is picked up by a tiny needle. In Dolly’s case, the differentiated cell was an udder cell from an adult donor . The cell is injected into the egg cell and a small electrical pulse is used to fuse the nucleus into its new environment and to kick-start cell division . The egg cell and differentiated cell fuse. You can see in this image that the egg cell now has a nucleus (upper centre) . The embryo is implanted into the uterus of a surrogate female. She carries the clone to term .