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What is cloning?

Feb 5, 2002 | Killing Embryos

Cloning, also called “somatic cell nuclear transfer,” is a laboratory method that allows the creation of a new individual who has only a single genetic parent. Cloning has produced live births in several species of mammals, including sheep, cattle, pigs, goats, mice, and monkeys.

In cloning, the nucleus (containing an individual’s genetic code) is first removed from an egg cell and replaced with the nucleus taken from a body cell (such as a skin cell) of a donor. (The donor can be anybody.) This combination of two cells is then stimulated or “activated,” usually by an electric current. When successful, an embryo begins to develop — an embryo with virtually the same genetic makeup as that of the single parent who contributed the nucleus.

In November, the biotech firm Advanced Cell Technology claimed it had created several cloned human embryos, who died for unknown reasons after reaching only a six-cell stage. This firm and others hope to perfect techniques to keep the embryos alive for a least five days, at which point the embryonic body would consist of at least 150 cells, including a cluster of “stem cells” — cells that have the capacity to develop into many different types of specialized tissue. The researchers will then dissect the embryo to remove those stem cells — killing the embryo.

The head of Advanced Cell Technology, among others, has said he thinks that it would be ethically acceptable to create embryos and keep them alive for up to two weeks. Other researchers are working to develop an “artificial womb,” with the eventual aim of being able to artificially sustain an unborn child from conception to full term.

Categories: Killing Embryos