What Are Stem Cells?
Stem cells are cells that have the power to become, virtually, any type of cell. Now how could this happen? Well, they are undifferentiated cells which means they haven’t become any specific cell yet. Each type of cell, (such as blood cells, stomach cells, skin cells) divides and replicates into 2 identical cells. So, only blood cells can make blood cells, and only skin cells make skin cells, this is because each cell has a different structure which determines its function. In short, brain cells can't be located in one's skin cells and expect to do all the functions a skin cell does every day! However, stem cells can go down any path and become any type of cell. Now the question is raised, where do these stem cells come from? There are types of stem cells: adult stem cells and embryonic stem cells.
Stem cells what?video1
Embryonic:
The first signs of stem cells appear in the blastocyst phase of embryonic development, in which an embryo has only lived about 4-5 days. This research is usually done in a vitro fertilization clinic where embryos have been donated for research. An inner and outer cell mass is what a blastocyst is. The inner cell mass is called embryoblast and the outer cell mass is called trophoblast. While the trophoblast becomes part of the placenta, embryoblast are the cells that will differentiate and become different types of cells that will be able to function as their own organism. Embryonic cells are called totipotent cells, this means that these cells have “total potential” to become any cell.
Adult:
These cells are found in tissues which include: the brain, blood, bone marrow, blood vessels, skin, skeletal muscles, and the liver. They are not active and do not become active until there is a disease or an injury of tissues. Many scientists believe that they can only create the cells in the certain tissue they are located, but there has been found some evidence that they can become any cell.