Answer:
Explanation:
These stem cells come from eggs that have been fertilized in vitro during IVF procedure, and were donated for research with the consent of the donors.
They are pluripotent: they have the potential to differentiate into almost any cell in the body.
Found in most organs in an individual who has already been born, they are responsible for tissue renewal or repair of damage. They can renew themselves or differentiate into the cell types of the tissue of origin.
They are multipotent, thus limited in their ability to differentiate: they will only produce specific cell types (e.g. neural stem cells produce neurons and glia).
The research with embryonic stem cells starts with an embryo in its early stages that can't develop outside the womb. Some people consider this early embryo a human being and are against scientific research with it, while others think that it's not a human being yet and research is not harmful because it couldn't survive unless implanted. In addition, experimentation with embryos could induce unplanned genetic mutations that could cause clinical aberrations if the embryo were implanted and allowed to develop into an adult individual.
In contrast, adult stem cells are not really controversial as they are cells derived from tissues from grown individuals. The main ethical issues are related to donor consent to obtain the cells.
