There are three main types of stem cells, which are usually considered for their potential use in research and medicine. They differ in their ability to self-renew:
(i) Totipotent
            These stem cells have the potential to become any kind of cell in the body. After an egg is fertilized, it undergoes a series of divisions to become any kind of cell in the body. After an egg is fertilized, it undergoes a series of divisions to become an embryo and later a fetus. The cells that are formed during these first few divisions are totipotent i.e they can become any cell in the body.
(ii) Pluripotent
            This type of stem cell has the ability to become almost any kind of cell in the body-except the cells of the placenta or other supporting tissue of the uterus. Pluripotent stem cells result after totipotent stem cells undergo the first few divisions. Embryonic stem cells at te blastocyststage and fetal stem cells are pluripotent.
(iii) Multipotent
            These cells can give rise to several other cell types, but those types are limited to mostly cells of the blood, heart, muscle and nerves. These cells functions as a repair system for damaged tissue. Adult stem cells are a good example of multipotent stem cells.