What defines stem cells?

Stem cells are characterized as unspecialized cells that possess the remarkable ability to differentiate into a variety of specialized cell types. This unique property allows them to develop into different tissues and organs, making them essential for growth, development, and tissue repair in living organisms.

The term "unspecialized" is crucial because it indicates that stem cells have not yet taken on a specific role or function in the body, which distinguishes them from fully differentiated cells, such as muscle or nerve cells. This ability to differentiate into multiple cell types—be it blood cells, nerve cells, or muscle cells—makes stem cells foundational to many biological processes and a focus of medical research, particularly in regenerative medicine.

The other options either focus on specialized cells, suggesting that stem cells have specific functions, which contradicts their definition as unspecialized, or inaccurately state that they are only found in embryos, failing to acknowledge the existence of adult stem cells as well, which can also differentiate under the right conditions.