Pig and Human Embryos

Scientists at the Salk Institute have embarked on some creepy research.  They’re injecting human cells into pig embryos.  The half-pig, half-human hybrid embryos were grown to the four-week stage when there were small but distinct organs present.  The goal is to grow organs available for human transplant.  They have a long way to go before they’re ready for transplants, but somebody needs to address the issue of ethics.  At what point do the human cells outnumber the pig’s contribution and we’re left with some sort of science fiction result?  Other researchers are working to grow “human-friendly” organs in pigs that replace their regular ones.  The animals would then be euthanized before they harvest the transplantable organs.  This “science” could end up being an irreversible Pandora’s Box.