AP PSYCHOLOGY

Detailed explanation-1: -These stem cells are found in small numbers in most adult tissues, such as bone marrow or fat. Compared with embryonic stem cells, adult stem cells have a more limited ability to give rise to various cells of the body. Until recently, researchers thought adult stem cells could create only similar types of cells.

Detailed explanation-2: -Adult stem cells have been found in most parts of the body, including brain, bone marrow, blood vessels, skin, teeth and heart. There are typically a small number of stem cells in each tissue. Due to their small number and rate of division (growth), it is difficult to grow adult stem cells in large numbers.

Detailed explanation-3: -Stem cells mostly live in the bone marrow (the spongy center of certain bones). This is where they divide to make new blood cells. Once blood cells mature, they leave the bone marrow and enter the bloodstream. A small number of the immature stem cells also get into the bloodstream.

Detailed explanation-4: -Stem cells originate from two main sources: adult body tissues and embryos. Scientists are also working on ways to develop stem cells from other cells, using genetic “reprogramming” techniques.