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08 Stem Cells - News of the day Just what are stem cells...

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News of the day… Just what are stem cells? Well, you’ll learn that today… Here’s one exciting use of the reparative ability of stem cells… http://www.cbsnews.com/stories/2006/06/20/tech/main1734662.shtml Movie Time… YAY! http://www. youtube .com/watch? v=9eYyT_R5Br0 The science… Scientists at the National Institutes of Health cultured stem cells from partially paralyzed rats with spinal cord damage, and treated them with chemicals that caused them to turn into nerve cells The cells were then transplanted into the damaged regions of the spinal cord The rats were able to re-grow nerves in the damaged areas Only about 1.25% of the nerves where active and functioning, but this was enough for 11 out of 15 of the rats to regain partial mobility in their hind limbs Recent published reports on the isolation and successful culturing of the first human pluripotent stem cell lines have generated great excitement and have brought biomedical research to the edge of a new frontier. The development of these human pluripotent stem cell lines deserves close scientific examination, evaluation of the promise for new therapies, and prevention strategies, and open discussion of the ethical issues. In order to understand the importance of this discovery as well as the related scientific, medical, and ethical issues, it is absolutely essential to first clarify the terms and definitions. Stem Cells – What’s the big deal?
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What is a Stem Cell? Stem cells are unspecialized cells that can renew themselves indefinitely and develop into more mature, specialized cells. They are found in embryos during early stages of development, in fetal tissue, and more rarely, in some adult organs. Scientists are especially interested in embryonic stem cells because they are grown easily in the laboratory and appear to be capable of becoming any type of cell. Stem cells have the ability to divide for indefinite periods in culture and to give rise to specialized cells. A fertilized egg is totipotent , meaning that its potential is total. In the first hours after fertilization, this cell divides into identical totipotent cells. Approximately four days after fertilization and after several cycles of cell division, these totipotent cells begin to specialize, forming a hollow sphere of cells, called a blastocyst. The blastocyst has an outer layer of cells and inside the hollow sphere, there is a cluster of cells called the inner cell mass. The outer layer of cells will go on to form the placenta and other supporting tissues needed for fetal development. The inner cell mass cells will go on to form virtually all of the tissues of the human body. Although the inner cell mass cells can form virtually every type of cell found in the human body, they cannot form an organism because they are unable to give rise to the placenta and supporting tissues necessary for development in the human uterus. These inner cell mass cells are pluripotent — they can give rise to many types of cells but not all types of cells necessary for fetal development.
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