What are embryonic stem cells?
Eggs fertilized by sperm begin to divide into multiple cells, but do not begin to form organs and tissues for at least two weeks. During this early developmental period, the cells that will ultimately give rise to the developing fetus can be encouraged to grow indefinitely in the laboratory as stem cells that are not committed to any particular tissue. With the right mixture of hormones and growth factors, such laboratory-grown embryonic stem cells can be encouraged to become many types of adult cells such as: nerves, heart muscle, and insulin-producing cells. Animal models, such as mice, have been used to demonstrate the important therapeutic potential of these cells in treating the symptoms of such diseases as Parkinson’s Disease and Diabetes. There are two main problems with the use of embryonic stem cells for therapeutic purposes. First is the moral and ethical debate that surrounds the use of a fertilized human egg for research and therapy. Second is the potential for tissue rejec
Embryonic stem cells are blank, unspecialized cells found in a blastocyst. A blastocyst is a mass of 150 or so cells that is smaller than the period at the end of this sentence. It develops approximately 5-14 days after an egg is fertilized. Embryonic stem cells make up the inner cell mass of the blastocyst. Unlike adult stem cells, embryonic stem cells are “pluripotent.” These means they have the ability to grow into any and every cell in the body, with the exception of egg and sperm cells. They also have the ability to continue to multiply and exist indefinitely. Embryonic stem cells, also known as “Human embryonic stem cells” (HeSC), were first discovered in 1998. To date, research on them has not been well funded. But scientists believe that their versatility gives embryonic stem cells even greater potential than that of adult stem cells.
