|MadSci Network: Cell Biology|
Your understanding is partly correct, with the added feature that stem cells can continue to proliferate and generate more stem cells as well as to differentiate into more specialized cells. Stem cells are more or less operationally defined as a population of cells that continuously renews itself and gives rise to one or more specialized cell types. A little more information, which may be more than you wanted. Stem cells can generally be divided into embryonic stem cells and adult stem cells. Embryonic stem cells (ES cells) are derived from early embryos and can give rise to all embryonic cell types. Mouse ES cells are widely used to introduce defined genetic changes into mice; subsequent breeding leads to animals with the defined change in all cells. These have been used to model aspects of human genetic diseases. Adult stem cells have more limited potential, with distinct cells that repopulate the blood, or intestine, or skin, all tissues where cell turnover occurs normally. The stem cells provide replacements for the cells that die off. http://www.devbio.com/chap04/link0407.shtml A highly detailed dsicussion of stem cells is available at the NIH web site: http://www.nih.gov/news/stemcell/scireport.htm Although these are fairly recent source, this is a fast moving field. Serious ethical issues exist concerning the isolation and use of human stem cells. The use of adult stem cell populations avoids this problem, although these cells are thought to have a more restricted range of cell types that can be generated. Some reports suggest that these cells may have a wider potential than thought, but other workers have contradictory results. The following news release, although potentially baised, outlines some of this controversy; more information is likely to follow. mednews.stanford.edu/news_releases_html/2002/sepreleases/adultstemcell.html Good luck with your project.
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