Cloning is most efficient using non–stem cells

Fully matured cells can be used to clone animals; in fact, using such cells for this purpose may be more efficient than using stem cells, scientists report.

Since Dolly the cloned sheep was born in 1996, some scientists have speculated that the donor cells used to create her and other cloned animals were rare adult stem cells—immature cells that have the potential to create a multitude of other cell types.