A cell capable of differentiating into any type of cell is known as “totipotent”. For mammals, totipotent includes the zygote and products of the first few cell divisions. There are also certain types of cells that can differentiate into many types of cells. These cells are known as “pluripotent” or stem cells in animals (meristemic cells in higher plants).
While this type of cell can divide to produce new differentiated generations, they retain the ability to divide and maintain the stem cell population making them some of the most important cells.
Examples of stem and progenitor cells include:
Hematopoietic Stem Cells – These are from the bone marrow and are involved in the production of red and white blood cells as well as the platelets.
Mesenchymal Stem Cells – Also from the bone marrow, these cells are involved in the production of fat cells, stromal cells as well as a given type of bone cell.
Epithelial Stem Cells – These are progenitor cells and are involved in the production of certain skin cells.
Muscle Satellite Cells – These are progenitor cells that contribute to differentiated muscle tissue.
The process of cell differentiation starts with the fertilization of the female egg. As soon as the egg is fertilized, cell multiplication is initiated resulting in the formation of a sphere of cells known as the blastocyst. It’s this sphere of cells that attach to the uterine wall and continues to differentiate.
As the blastocyst differentiates, it divides and specializes to form a zygote that attaches to the womb for nutrients. As it continues to multiply and increase in size, the differentiation process results in the formation of different organs.