Nuclear Transfer

Nuclear Transfer is a form of cloning. The steps involve removing the DNA from an oocyte(unfertilized egg), and injecting the nucleus which contains the DNA to be cloned. In rare instances, the newly constructed cell will divide normally, replicating the new DNA while remaining in a pluripotent state. If the cloned cells are placed in the uterus of a female mammal, a cloned organism develops to term in rare instances. This is how Dolly the Sheep and many other species were cloned. Alternatively, if cells are extracted from the cloned cells during very early embryonic stages (blastocyst or morula), embryonic stem cells can be created. These cells can be grown in laboratories indefinitely and can theoretically be made into any of the 200+ cell types in the mammalian body, and thus are an extraordinary tool for biologists as well as a therapeutic agent with the potential to treat currently untreatable medical conditions.

Tools & Reagents
Nuclear transfer is a delicate process that is a major hurdle in the development of cloning technology! Materials used in this procedure are a microscope, a holding pipette (small vacuum) to keep the oocyte in place, and a micropipette (hair-thin needle) capable of extracting the nucleus of a cell using a vacuum. For some species, such as mouse, a drill is used to pierce the outer layers of the oocyte.

Various chemical reagents are used to increase cloning efficiency. Microtubule inhibitors, such as nocodazole, are used to arrest the oocyte in M phase, during which its nuclear membrane is dissolved. Chemicals are also used to stimulate oocyte activation.

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