Adult stem cells are cells that are tissue-specific. Although found in adults, children, and fetuses, adult stem cells are so called because they are specialized cells thought to be found in most of the body's tissues. These remain specific to their tissue of origin, but have the power to become any cell. For example, adult stem cells in bone marrow can become red or white blood cells but can not become brain cells. Adult stem cells have the ability to divide or self-renew, which makes them key to study since it has the potential to create an almost unlimited number of necessary cells. Adult stem cells are derived from adult tissue samples, and can also be derived from cord blood extracted after the birth of an infant.