Stem cells
A cell found in foetuses, embryos and some adult tissues that can give rise to a wide range of other cells. are cells that have not undergone When an unspecialised cell becomes a more specialised cell type.. A cell which has not yet become The formation of new and distinct species in the course of evolution. is called undifferentiated.
An embryo develops from a fertilised egg. Cells at early stages in the development of the embryo are stem cells.
If A type of stem cell found in the embryo, capable of dividing into almost any cell type. are removed from the embryo they will differentiate into any cell type.
Some A type of stem cell found in specific locations in adults. Adult stem cells can only differentiate into a limited number of related cell types. remain in the bodies of adults. These are found in limited numbers at certain locations in the body. Adult stem cells can be found in:
- nose
- brain
- eyes
- blood
- heart
- liver
- Soft tissue found inside bones that produces new blood cells.
- skin
- muscle
Adult stem cells can differentiate into related cell types only. So bone marrow cells can differentiate into blood cells and cells of the The body's defence system against entry of any foreign body, including pathogens and agents such as pollen grains. The role of the immune system is to prevent disease., but not other cell types.
Stem cells in plants
Cell division in plants occurs in regions called A region in plant shoots and roots in which cells are dividing, and so are undergoing mitosis.. 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. They enlarge and develop a A space within the cytoplasm of plant cells that contains cell sap..
Discover more about stem cells with Dr Alex Lathbridge
Listen to the full series on 大象传媒 Sounds.
Discover how cells differ in plants and animals and why they're really useful for scientists.