ppt of stem cell theoretical

Stem cells are undifferentiated cells that can differentiate into specialized cells and can divide (through mitosis) to produce more stem cells.
They are found in multicellular organisms. In mammals, there are two broad types of stem cells:
Embryonic Stem Cells, which are isolated from the inner cell mass of blastocysts, and
Adult Stem Cells, which are found in various tissues.

In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing adult tissues.
In a developing embryo, stem cells can differentiate into all the specialized cells: ectoderm, endoderm and mesoderm but also maintain the normal turnover of regenerative organs, such as blood, skin, or intestinal tissues.
stem cells divisions are always asymmetric, that is, one daughter cell remains as a stem cell while the other becomes committed to a path that leads to differentiation.

Stem cells of many tissues are found in specific locations where the microenvironment helps maintain their uniquely undifferentiated properties; they are often rare and not noticeable by routine histological methods.