The term cloning describes a number of different processes that can be used to produce genetically identical copies of a biological entity1.The copied material,which has the same genetic make-up as the original,is referred to as a clone. Researchers have cloned a wide range of biological materials,including genes,cells,tissues and even entire organisms,such as a sheep. Over the last 50 years,scientists have conducted cloning experiments in a wide range of animals using a variety of techniques.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.Shortly after that,researchers produced the first genetically identical cows,sheep and chickens by transferring2 the nucleus of a cell taken from an early embryo into an egg that had been emptied of its nucleus.