| Stem Cells | A Discussion of the Basics | BIOL 101-SEC 6981 | Katrina Helldorfer | 3/22/2013 |

Medical science has gained incredible ground in recent years thanks to advancements offered by the burgeoning study of stem cells. Stem cells are a unique type of cell that is known as ‘undifferentiated’, which means that they can become any kind of cell in the body. There are three kinds of stem cells. The first kind is adult stem cells, and these exist throughout the adult body. The second category is embryonic stem cells, which are harvested from embryonic tissue and are the most versatile (Crosta). The third group of stem cells is called embryonic ‘fetal’ germ cells. This last group, fetal germ cells, develop into gametes (sperm and eggs) and are not generally used by scientists for research purposes. The designations of ‘embryonic’ and ‘adult’ are used to refer to the origin of stem cells; explaining whether they originate from an embryo or adult tissue (Miracle Cell | The Stem Cell Controversy).
Each of the three types of stem cells are unspecialized and derived from blastocysts. During the development of the fetus, stem cells differentiate, changing to all the specialized calls that exist in the body (Simon, Dickey, Reece, & Campbell, 2013). They have the ability to renew themselves indefinitely through cell division, and scientists have found that they can be used to regenerate and repair diseased and damaged tissues and organs.
Adult stem cells are harvested from adult tissue. Since they have already passed the blastocyst stage, they are considered to be only partially differentiated. One cell still has the potential to change to specialized cells, but the different types are limited. For example, a stem cell generated in bone marrow has the potential to become different kinds of blood cells.(Simon, Dickey, Reece, & Campbell, 2013).
Embryonic stem cells (ES cells) are more controversial than adult stem cells. They are harvested from an embryo that is 4-5 days old, and about 150 stem cells are produced. At this age, the cells are pluripotent, which means that they can either change into specialized cells or they can continue to divide as stem cells indefinitely (Mayo Clinic, 2010). When stem cells are under the right conditions and are assisted to divide indefinitely, this is referred to as a ‘stem cell line’. ES cells are harvested from embryos that are developed as ‘surplus embryos’ created naturally in the process of in vitro fertilization (IVF). During IVF, eggs are fertilized in a laboratory culture dish, and, once they have begun to grow and develop into ‘pre-embryos’, are then implanted into the women’s uterus. This procedure results in ultimately unused embryos that can safely be used by scientists as a source for embryonic stem cells (Miracle Cell | The Stem Cell Controversy).
However, harvesting embryonic stems cells is controversial because the embryo is destroyed in the process. Groups have come forward arguing that an embryo should be considered a person, and that it is ethically wrong to destroy a potential member of a future generation only to help a person of this