This question has already been answered by ethicists. The cells are human cells. They are not going to grow and turn into an elephant or a mouse. They are going to grow into a human, therefore it is always a human. This stance is further supported by the stem cell industry. An entire sector of industry has been created out of the cultulivation of human stem cells which are *extremely* valuable and are finding to have enormous potential in application. Edit: This was the explination given to me in Grad School by a rep for a stem cell research company. Our class had to create a policy report on an issue they were having around ethics in using actual stem cells vs. synthetic stem cell material and potential funding issues. The entire class was given the same info then we each created our policy solution and present it to him and defended it. I went to an extremely liberal all womens college. Everyone else demanded that the company stick to real stem cells as a way to reinforce the "my body/my choice" movement and to find funders that aligned with this belief. Ugh..The rep looked like he would naw his arm off. Then I presented in support of synthetic to avoid the abortion conflict and many feminist connotations all together to access funding across the board. He jumped up and said, "you get it. This is exactly right and what we decided to do". You could see the steam rolling out of the ears of half the class. IT.WAS.GLORIOUS.