From the Greek klon meaning a cutting such as is used to propagate plants, this is essentially a form of asexual reproduction. In essence the technique consists of destroying the nucleus of the egg and replacing it with the nucleus from a body cell of the same species – either a male or a female. This provides the egg with a full complement of CHROMOSOMES and it starts to divide and grow just as it would if it had retained its nucleus and been fertilised with a spermatozoon. The vital difference is that the embryo resulting from this cloning process owes nothing genetically to the female egg. It is identical in every respect with the animal from which the introduced nucleus was obtained.

Many animal clones have been produced and researchers have cloned the first human embryo – which grew to six cells – with the aim of providing STEM CELLS for therapeutic use.