Mice cloned using fertilized eggs
Unfertilized eggs have long been the limiting resource for attempts to make genetically tailored human embryonic stem cells. If a new technique for cloning mice from fertilized eggs works in humans, they might not be necessary.
Few women are willing to give their unfertilized eggs to scientists. But many researchers believe these are the only suitable source material for making genetically tailored human embryonic stem cells (ES cells) — cells that could help us understand the biology of disease or, perhaps some day, be used in cell-transplant therapy. The shortage of eggs has spawned bitter debate over whether women should be allowed to donate, barter, or even sell their eggs to research laboratories.
