The pluripotency of a stem cell is the ability of a stem cell to develop into more than one mature cell or tissue type, but it cannot form an organism.

A stem cell is an unspecialized cell that can divide without limit as needed and can, under specific conditions, differentiate into specialized cells. They can differentiate into different cell types. The potency of the stem cell determines how many different cell types a stem cell can become. As cells become more differentiated, the potency of the cell gets more narrow (from totipotent to pluripotent to multipotent).

1. The first embryonic cells that arise from the division of the zygote are the totipotent stem cells; they have the potential to differentiate into any of the cells needed to enable an organism to grow and develop.
2. The embryonic cells that develop from totipotent stem cells and are precursors to the fundamental tissue layers of the embryo are the pluripotent stem cells. A pluripotent stem cell is one that has the potential to differentiate into any human tissue but cannot support the full development of an organism. 
3. Pluripotent cells then become slightly more specialized and are referred to as multipotent cells. A multipotent stem cell has the potential to differentiate into different types of cells within a given cell lineage or a small number of lineages, such as a red blood cell or white blood cell. 

During embryonic development, the pluripotent cells of the inner cell mass (the cell cluster inside the hollow sphere in the blastocyst) go on to form virtually all of the tissues of the human body. However, they cannot support the full development of an organism. 

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Key Points

• A stem cell is an unspecialized cell that can differentiate into specialized cells.

• Different types of stem cells exhibit varying abilities to differentiate into specialized cells (from the most unlimited stem cell to the most restricted): totipotent, pluripotent, to multipotent.

• Totipotent cells have the potential to differentiate into any of the cells needed to enable an organism to grow and develop.

• Pluripotent cells have the potential to differentiate into any human tissue but cannot support the full development of an organism.

• A multipotent stem cell has the potential to differentiate into different types of cells within a given cell lineage or a small number of lineages.

Key Terms

differentiate: to produce distinct cells, organs or to achieve specific functions by process of development

potency: a term used to describe the ability or inability of a stem cell to differentiate into different cell types

totipotency: the ability of a cell to produce differentiated cells upon division

pluripotent: the ability of a cell to develop into more than one mature cell or tissue type, but not all

multipotent: the ability of a cell to differentiate into various cells within a particular lineage

blastocyst: the mammalian blastula formed during development where the inner cell mass can be found which forms the embryo

inner cell mass: a mass of cells within a primordial embryo that will eventually develop into the distinct form of a fetus in most eutherian mammals