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.