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Unformatted text preview: Transfer adult nucleus
to enucleated egg Culture to
early embryo Blastocyst Implant in
foster mother FIGURE 17.25 Cloning by somatic cell nuclear transfer (A) The nucleus of
an adult somatic cell is transferred to an unfertilized egg from which the normal
egg chromosomes have been removed (an enucleated egg). The egg is then cultured to an early embryo and transferred to a foster mother, who then gives birth
to a clone of the donor of the adult nucleus. (B) Dolly (the adult sheep, left) was
the first cloned mammal. She is shown with her lamb, Bonnie, who was produced
by normal reproduction. (Photograph by Roddy Field; courtesy of T. Wakayama
and R. Yanagimachi.) Somatic Cell Nuclear Transfer
Clone T he isolation of human embryonic stem cells in 1998 followed the first
demonstration that the nucleus of an adult mammalian cell could give rise
to a viable cloned animal. In 1997 Ian Wilmut and his colleagues initiated a
new era of regenerative medicine with the cloning of Dolly the sheep (Figure 17.25). Dolly arose from the nucleus of a mam...
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