Dolly the sheep will remain one of a kind—at least for the time being.
Ian Wilmut of the Roslin Institute near Edinburgh, whose team created Dolly from
the udder cell of a six-year-old ewe, says that he has no plans to repeat the
procedure of cloning an adult animal. “Dolly is very much a one-off,” he
says.
Investigation into how an adult cell can develop into a new animal will have
to wait or be taken up by other researchers. Instead, Wilmut says he will
concentrate on cloning using cells taken from 30-day-old embryos.
