Monitoring and maintaining health - non-communicable - OCR GatewayStem cells

Stem cells in humans

Stem cells are cells that have not undergone differentiation. A cell which has not yet become specialised is called undifferentiated.

An embryo develops from a fertilised egg. Cells at early stages in the development of the embryo are stem cells.

If stem cells are removed from the embryo – called embryonic stem cells – they will differentiate into any cell type.

Some stem cells remain in the bodies of adults – adult stem cells.

Adult stem cells are found in limited numbers at certain locations in the body, including the:

• brain
• eyes
• blood
• heart
• liver
• bone marrow
• skin
• muscle

Adult stem cells can differentiate into related cell types only, for instance, bone marrow cells can differentiate into blood cells and cells of the immune system, but not other cell types.

Stem cells in plants

Cell division in plants occurs in regions called meristems.

The main meristems are close to the tip of the shoot, and the tip of the root.

In a growing shoot, new cells are being produced continuously near the tip. As the cells become older, further away from the tip, they become differentiated – they enlarge and develop vacuoles.