To make a clone, scientists transfer the DNA from an animal’s somatic cell into an egg cell that has had its nucleus and DNA removed. The egg develops into an embryo that contains the same genes as the cell donor. Then the embryo is implanted into an adult female’s uterus to grow.

The nucleus of a cell from one mouse was injected through a tiny needle into an egg donated by a second mouse. The egg’s original genetic package was removed. The donor nucleus came from cumulus cells, which surround the developing eggs in the ovaries of female mice. The technique gave Cumulina her name.

Nuclei from these cells were put into egg cell devoid of their original nuclei in the Honolulu cloning technique. All other mice produced by the Yanagimachi lab are just known by a number. Cumulina was able to produce two healthy litters. She was retired after the second.

1998

The pig, he said, is considered the best species to use for growing organs to replace ailing hearts, livers and kidneys in humans. “The pig organs roughly match the size of human adult organs,” Perry said. “They also are amiable to transplant surgery.”

Dolly the Sheep

You’ve probably heard of Dolly the sheep. Now, meet Elizabeth Ann, the black-footed ferret. Scientists have successfully cloned an endangered black-footed ferret, using preserved cells from a long-dead wild animal. This is the first time any native endangered species has been cloned in the United States.

She was born on 5 July 1996 and died from a progressive lung disease five months before her seventh birthday (the disease was not considered related to her being a clone) on 14 February 2003. She has been called “the world’s most famous sheep” by sources including BBC News and Scientific American.

Myth: Offspring of clones are clones, and each generation gets weaker and weaker and has more and more problems. No, not at all. A clone produces offspring by sexual reproduction just like any other animal.

However, because cloning is still very expensive, it will likely take many years until food products from cloned animals actually appear in supermarkets. Another application is to create clones to build populations of endangered, or possibly even extinct, species of animals.

The society’s report outlined the scientific arguments against human reproductive cloning, explaining that the technique is ineffective (only a 1% success rate in mammals) and unpredictable and results in a high percentage of fetal deaths.

But human cloning never happened. The reason is clear in retrospect. In the basic cloning procedure, like that used to create Dolly the sheep in 1996, scientists take an entire adult cell and inject it into an egg that’s been relieved of its own DNA. The resulting embryo is a clone.

Livestock species that scientists have successfully cloned are cattle, swine, sheep, and goats. Scientists have also cloned mice, rats, rabbits, cats, mules, horses and one dog. Chickens and other poultry have not been cloned.