A group of American and Canadian biologists is debating whether to recommend stem cell experiments that would involve creating a human-mouse hybrid. ... animals born from the experiment would be chimeras ... with human cells distributed throughout their body. At least two biologists in the group that is discussing the experiment said they believed that it was premature or unethical and could stir policy makers to limit further stem cell research or ban it. Stem Cell Mixing May Form a Human-Mouse Hybrid | 
