A stem cell could be the cure to many diseases once thought incurable. These microscopic cells have the potential to form almost any dead or damaged cell in the body. The controversy begins when the stem cells are gathered. In most cases, a human embryo must be killed to harvest these cells. Some argue that these embryos are not living human beings, while others say it is murder. Even though these cells could cure diseases, it is still wrong to kill the embryos.
             A stem cell develops when a sperm fertilizes an egg and forms an embryo. This embryo begins to divide and forms a sphere called a blastocyst. The cells start to become different from their neighbors. This process, called differentiation, allows the embryo's cells to become the different organs of the embryo such as liver, skin and nerve cells. Scientists hope to be able to control this process to form a needed tissue.
             There are three different stages of a stem cell. When one is less than four days old, it is called totipotent. This means it has total potential to form a human being if it were isolated from the other cells and planted into a uteruse. After four to five days, the group of cells is called pluripotent, which means it no longer can form a human being if it's cells were separated. Later, it becomes multipotent. It has the potential to form different kinds of cells, but not all. According to scientists almost any disease could be cured with these stem cells. Diseases happen because certain cells in the body are not functioning properly or overwhelmed. For example, if someone had a heart attack, his heart muscles could be replaced with healthy ones grown from stem cells. Scientists also hope to be able to grow new organs from the stem cells.
             There are five ways to obtain stem cells. The first way is by using leftovers from fertility clinics. During in-vitro fertilization, these clinics fuse sperm and eggs. Thousands of unwanted emb
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