Our bodies are the ultimate factory. Every cell has its specific job to do and is shaped to do that job perfectly. Muscle cell is a muscle cell and only a muscle cell. A nerve cell will only ever be a nerve cell. And a red blood cell will only ever be a red blood cell. The fate of each cell is determined during the embryo stage and then cannot be changed. However cutting-edge research made a major discovery for modern science. There are these wonderful cells that exist called stem cells. These cells have the ability to become any type of cell because they are not specialized. Scientists were hugely excited by their discovery because they can be used to repair damaged organs, bones or cartilage. They could also be used to help treat diseases such as by making new brain cells to treat people with Parkinson's disease or they could be used to repair damaged immune systems and even reverse paralysis or regrow lost limbs. The discovery of stem cells is huge for modern medicine and could have a massive impact. There are two types of stem cells in humans, embryonic stem cells and adult stem cells. Embryonic stem cells are on specialized cells that can develop into any type of cell. But stem cells are also on specialized cells. But whilst they can develop into many types of cells, unlike embryonic stem cells, they cannot develop into every type of cell. Adult stem cells come from tissues such as bone marrow. As in the name, embryonic stem cells can be removed from unused embryos, such as those lived over from fertility treatments, for example. Whilst the discovery of stem cells offers huge potential for modern medicine, there are many social and ethical considerations that need to be taken into account. A lot of research was and still is needed to find out exactly how they work and how we can control them to do what we want and not just grow uncontrollably. Stim cells are already being used in treatments. Currently in 2016, there is a trial study underway to use stem cells to reboot the immune system of multiple sclerosis sufferers to enable them to regain some mobility. Using stem cells to treat diseases and conditions of the blood and immune system are currently the most widely used stem cell treatment. Over 26,000 patients are treated with blood stem cells in Europe annually. A new stem cell treatment has recently been approved for repairing damage to the cornea. Stim cell treatments are also being used in rhino conservation efforts, as well as other endangered species. One big social and ethical debate around stem cells is therapeutic cloning. This is the concept of cloning a patient, growing an embryo from the cloned cells, and then extracting stem cells from the embryo to grow a specific organ needed by the patient. Stim's body would not reject this organ, as it is made from the patient's own cells. The ethical debate focuses on defining when does life start, is the embryo alive, people also don't like the idea of us playing God. We will look at the process of cloning in another video. Unspecialized stem cells also exist in plants and can develop into the cells of flowers, roots or leaves. Unlike in animal cells, some plants cells do remain unspecialized and can then develop into any type of plant cell. The unspecialized plant cells group together into structures called meristems, whereas animals stop growing in size when they are adults, plants do not. This is because meristems divide to produce cells, thus enabling plants to continue to grow both in height and width throughout their lives. They also produce cells that develop into flowers and leaves. So from this video, you should know that stem cells are present in embryonic and adult animal cells, and in meristems and plants. Those cells are unspecialized and can develop into a range of different cell types for development, growth and repair. In animals, embryonic stem cells can turn into any cell type, whereas adult stem cells which are found in bone marrow can only turn into sum cells.