An embryo develops from a fertilised egg. Cells at early stages in the development of the embryo are stem cells.
If 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 - known as adult stem cells. Adult stem cells are found in limited numbers at certain locations in the body.
Adult stem cells can be found in several regions of the body, including the:
Cell division in plants occurs in regions called meristems.
Cells of the meristem can differentiate to produce all types of plant cells at any time during the life of the plant.
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.