Early in stem cell research, the only available source of stem cells was believed to be embryos (fertilized eggs). This source is still quite controversial, since an embryo is destroyed in order to obtain the Stem Cells. Later on, researchers thought that bone marrow was the only other source of adult Stem Cells, but then determined that bone marrow has a low concentration of stem cells (1 in 100,000 cells). In the late 1990’s it was discovered that there are many tissues that contain stem cells, which are capable of transforming into most of the major types of cells found in tissues throughout the body. It is now well established that there is a high concentration of stem cells in fat that can be purified as a rich source of cells for assisting healing.