There currently is no solid scientific evidence that anyone has cloned human embryos. In addition, a rhesus monkey has been cloned by embryo splitting.ĭespite several highly publicized claims, human cloning still appears to be fiction. Two years later, researchers in Japan cloned eight calves from a single cow, but only four survived.īesides cattle and sheep, other mammals that have been cloned from somatic cells include: cat, deer, dog, horse, mule, ox, rabbit and rat. After 276 attempts, Scottish researchers finally produced Dolly, the lamb from the udder cell of a 6-year-old sheep. It was not until 1996, however, that researchers succeeded in cloning the first mammal from a mature (somatic) cell taken from an adult animal. Shortly after that, researchers produced the first genetically identical cows, sheep and chickens by transferring the nucleus of a cell taken from an early embryo into an egg that had been emptied of its nucleus. In 1979, researchers produced the first genetically identical mice by splitting mouse embryos in the test tube and then implanting the resulting embryos into the wombs of adult female mice. Over the last 50 years, scientists have conducted cloning experiments in a wide range of animals using a variety of techniques. Reproductive cloning may require the use of a surrogate mother to allow development of the cloned embryo, as was the case for the most famous cloned organism, Dolly the sheep. This young animal is referred to as a clone.
Ultimately, the adult female gives birth to an animal that has the same genetic make up as the animal that donated the somatic cell.
In both processes, the egg is allowed to develop into an early-stage embryo in the test-tube and then is implanted into the womb of an adult female animal. In the second approach, they use an electrical current to fuse the entire somatic cell with the empty egg. In the first method, they remove the DNA-containing nucleus of the somatic cell with a needle and inject it into the empty egg. Researchers can add the DNA from the somatic cell to the empty egg in two different ways.
They then transfer the DNA of the donor animal's somatic cell into an egg cell, or oocyte, that has had its own DNA-containing nucleus removed.
In reproductive cloning, researchers remove a mature somatic cell, such as a skin cell, from an animal that they wish to copy.