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How did somatic cell nuclear transfer make modern cloning possible?

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Replica of a woolly mammoth with long curved tusks and shaggy fur on display in a museum exhibit, set against a dramatic painted landscape backdrop. — de-extinction The woolly mammoth (*Mammuthus primigenius*)—represented here by a replica in a Canadian museum—is an example of an extinct species that someday could be resurrected through de-extinction.

Somatic cell nuclear transfer (SCNT) made modern cloning possible by providing a method to reprogram a differentiated somatic (body) cell nucleus into a state capable of guiding embryonic development.12

In this technique, the nucleus of a somatic cell is transferred into an enucleated egg—an egg cell that has had its own nucleus removed. Once inside, cytoplasmic factors within the egg reprogram the somatic nucleus to function like a zygote nucleus. This process allows the reconstructed cell to develop into a blastocyst, which can then be implanted into a surrogate mother to produce a clone.123

This breakthrough was famously demonstrated in 1996 with the birth of Dolly the sheep, the first mammal cloned using SCNT. In the context of de-extinction, SCNT offers a potential pathway to resurrect extinct species by using preserved tissues from the extinct animal as nuclear donors for the enucleated eggs of a closely related living species. While this technology represents a significant scientific advancement, it is essential to approach its application with deep ethical responsibility, considering the welfare of the animals involved and the broader ecological consequences of altering natural history.123