What role do stem cells play in development?

Stem cells play a crucial role in development because they possess the unique ability to develop into specialized types of cells. This process, known as differentiation, allows stem cells to give rise to various cell types that perform specific functions in the body. For instance, embryonic stem cells are pluripotent and can differentiate into any cell type, including muscle, nerve, or blood cells. Adult stem cells, though more limited in their potential, still contribute to tissue maintenance and repair by differentiating into specialized cells as needed.

On the other hand, while protective barriers in tissues are important for function, they are a role for differentiated cells, not stem cells. Stem cells do not maintain the status quo but are involved in dynamic processes like growth and differentiation. Additionally, rather than stopping cellular growth, stem cells are vital for growth and development, especially during the early stages of an organism's life.