What are stem cells?
Stem cells are cells that can become many types of cells. They can be found in three different sources: embryos (embryonic stem cells) and in adult bodies (adult stem cells, progenitor or somatic stem cells), and in umbilical cord blood (cord blood stem cells). When a zygote forms it undergoes mitosis and the cells divide, these cells are totipotent and are able to develop into an organism. For about 6 days the cells continue to undergo mitosis, which creates hundreds of cells, called the blastocyst. The outer layer of the blastocyst, the trophoblast, later becomes the placenta. Inside the trophoblast are cells called the inner cell mass, these are the embryonic stem cells. These stem cells are pluripotent, they can become any cell in the body. As they grow, pluripotent stem cells in the embryo become multipotent, specialized, stem cells. Somatic stem cells are placed throughout the adult human body in small amounts for specific organs and processes for the area which they are located. They cannot renew themselves as well as embryonic stem cells can. Cord blood
Stem cells have the ability to cure many diseases because they can renew themselves, and are able to differentiate into specialized cells, even if they are unspecialized.