And a great example of this differentiation process is our immune system. We know that our immune system consists of many different types of cells that have not only different structures and different sizes but also have their own unique function. So we have this single stem cell known as the hematopoietic stem cell that produces red blood cells and white blood cells. And we have many different types of white blood cells. For example, we have macrophages which are these large cells that engulf pathogenic agents and break down those pathogenic agents. But macrophages are not the only wide blood cells.