Cow Eggs with Human Cells
British researchers were given approval to conduct human-animal hybrid research in 2008, a decision that researchers touted would give them the ability to possibly find a cure for Parkinson’s disease.
Before, only human cells were allowed to be injected into human eggs, but the researchers argued that animal eggs are much more available. After given permission, researchers went to work using cow eggs.
The nucleus of the cow egg -- the source of most DNA and shown here in blue -- was removed, and replaced with the nucleus of a human cell such as a skin cell. Once the egg was allowed to develop and multiply it would become a early-stage cloned embryo called a blastocyst. Scientists could then extract the stem cells from this blastocyst to use in disease treatments.