A U.S. research team claims to have created embryonic stem cells from unfertilized mouse eggs for the first time.

Dr. George Daley of Children's Hospital in Boston said in a paper released in the magazine Science that his team successfully extracted stem cells from embryos created from mouse eggs. The stem cells that were then injected into the mice grew into cells.

He said he the embryonic stem cells were then transplanted to other mice without symptoms of rejection.

Daley said the experiment using mouse eggs, which he claims has a seventy-percent success rate, is far more effective than the existing cloning method via somatic cell transfer.