Stem cells are special human cells that are able to develop into many different cell types. This can range from muscle cells to brain cells. In some cases, they can also fix damaged tissues. Researchers believe that stem cell-based therapies may one day be used to treat serious illnesses such as paralysis and Alzheimer disease. Embryonic stem cells.
Adult stem cells are undifferentiated cells that reside among differentiated cells in a tissue or organ. They have the ability to renew themselves and differentiate into specialized cell types. Not like embryonic stem cells which can become all cell types, adult stem cells are limited to differentiating into distinct cell types of their tissue of origin, and they are therefore multipotent or unipotent stem cells. The primary roles of adult stem cells are to maintain and repair the tissue in which they reside.
In multicellular organisms , stem cells are undifferentiated or partially differentiated cells that can differentiate into various types of cells and proliferate indefinitely to produce more of the same stem cell. They are the earliest type of cell in a cell lineage. They are usually distinguished from progenitor cells , which cannot divide indefinitely, and precursor or blast cells, which are usually committed to differentiating into one cell type. In mammals , roughly 50— cells make up the inner cell mass during the blastocyst stage of embryonic development, around days 5— These have stem-cell capability.
Jump to navigation. For many years, researchers have been seeking to understand the body's ability to repair and replace the cells and tissues of some organs, but not others. After years of work pursuing the how and why of seemingly indiscriminant cell repair mechanisms, scientists have now focused their attention on adult stem cells. It has long been known that stem cells are capable of renewing themselves and that they can generate multiple cell types. Today, there is new evidence that stem cells are present in far more tissues and organs than once thought and that these cells are capable of developing into more kinds of cells than previously imagined.