Final answer:
Stem cells are initially totipotent and can differentiate into any cell type, including embryonic stem cells. They specialize by turning off unnecessary genes but can continue to divide and create new stem cells. Pluripotent stem cells can become multiple cell types, whereas multipotent stem cells are restricted to certain tissues.
Step-by-step explanation:
Stem cells have the remarkable ability to diversify and become specialized cells. The initial cells formed right after fertilization, known as totipotent stem cells, can turn into any type of cell, be it muscle, skin, or nerve cells, and these include embryonic stem cells. As stem cells specialize, certain genes not needed for their specific functions get turned off, but this does not mean these genes will never be active again; they just won't become proteins in that particular specialized cell's lifetime. Hierarchically, below totipotent stem cells are pluripotent stem cells, which can give rise to multiple cell types, but cannot develop into an entire organism, while multipotent stem cells are even more specialized and can differentiate only into a range of cells within a certain tissue type. Adult stem cells, like hematopoietic stem cells in bone marrow, are typically multipotent and give rise to related cell types such as red and white blood cells.