Narrator: This is Science Today. The use of embryonic stem cells for research has been controversial, but now scientists are reporting a technique that does not require the destruction of human embryos. Still, Dr. Judith Gasson, co-director of UCLA's Institute for Stem Cell Biology and Medicine, says it's important for people to understand the source of embryonic stem cells used in research.
Gasson: Embryonic stem cells come from fertility clinics. Eggs and sperm are mixed together in a test tube and then they're frozen in liquid nitrogen and some number of those will be implanted into the woman and typically what remains in those freezers is basically discarded. So, rather than discarding those tissues that were produced, they can be donated to research and that's the source of embryonic stem cells – it's not coming from fetuses. The cells have never even been inside a human being, so I think that's important for people to understand.
Narrator: For Science Today, I'm Larissa Branin.