Some tissues in the adult body, such as the epidermis of the skin, the lining of the small intestine , and bone marrow , undergo continuous cellular turnover. The stem cells exist in niches formed by other cells, which secrete substances that keep the stem cells alive and active. Some types of tissue, such as liver tissue, show minimal cell division or undergo cell division only when injured. In such tissues there is probably no special stem-cell population, and any cell can participate in tissue regeneration when required. The epidermis of the skin contains layers of cells called keratinocytes. Only the basal layer, next to the dermis, contains cells that divide.
Understanding Adult and Embryonic Stem Cell Research
Stem cell - Wikipedia
Adult stem cells are undifferentiated cells found throughout the body that divide to replenish dying cells and regenerate damaged tissues. Research into adult stem cells has been fueled by their abilities to divide or self-renew indefinitely and generate all the cell types of the organ from which they originate — potentially regenerating the entire organ from a few cells. Unlike embryonic stem cells, the use of adult stem cells in research and therapy is not controversial because the production of adult stem cells does not require the destruction of an embryo. The rigorous definition of a stem cell requires that it possesses two properties: Self-renewal - the ability to go through numerous cycles of cell division while maintaining the undifferentiated state.
Stem cells and derived products offer great promise for new medical treatments. Learn about stem cell types, current and possible uses, ethical issues, and the state of research and practice. You've heard about stem cells in the news, and perhaps you've wondered if they might help you or a loved one with a serious disease.
The primary role of adult stem cells in humans is to maintain and repair the tissue in which they are found. Stem cells are very flexible cells, sometimes considered immature, that have not developed to a final specialized cell type like skin, liver, heart, etc. Since they have not yet specialized, stem cells can respond to different signals and needs in the body by becoming any of the various cell types needed, e. In that sense they are a bit like a maintenance crew that keeps repairing and replacing damaged or worn out cells in the body. Microscopic in size, stem cells are big news in medical and science circles because they can be used to replace or even heal damaged tissues and cells in the body.