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Stem Cells are unspecialised cells that can develop into any type of cell. They divide by mitosis to become new cells which then become
specialised. This process is called differentiation.
TOTIPOTENCY: the ability to produce all cell types, including all the specialised cells in an organism and extraembryonic cells (cells of the placenta and
PLURIPOTENCY: the ability to produce all the specialised cells in an organism (but not extraembryonic cells.)
Sources of stem cells
ADULT STEM CELLS
Obtained from the body tissue of an adult e.g. in bone marrow.
Obtained in a relatively simple operation very little risk but a lot of discomfort. Donor is anaesthetised, a needle is inserted into the
centre of a bone and a small quantity of bone marrow is removed.
Adult stem cells aren't as flexible as embryonic stem cells can only develop into a limited amount of cells.
EMBRYONIC STEM CELLS
Obtained from early embryos and can be created by using in vitro fertilisation egg cells are fertilised by sperm outside the womb.
Once the embryos are 4 to 5 days old, stem cells a can be removed and the rest of embryo destroyed.
They can develop into any type of cell.
Obtaining stem cells from embryos raises several ethical issues because the procedure results in the destruction of an embryo that's viable. Many
people believe that at the moment of fertilisation a genetically unique individual is formed that has the right to life.
Uses of stem cells
They could be used to replace damaged tissues in a range of diseases. E.g. they could be used to repair damaged nerve tissue in spinal cord
Stem cells could be used to grow organs for those people awaiting transplants.
They could improve peoples QOL e.g. stems cells could be used to replace damaged cells in the eyes of blind people.
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To help society make decisions about the use of stem cells in medicine, regulatory authorities have been established to consider the benefits and
ethical issues surrounding embryonic research, their work includes:
Looking at proposals of research to decide if they should be allowed.
Licensing and monitoring centres involved in embryonic research which ensures that only fully trained staff carry out research.
Producing guidelines and codes of practice ensures methods of extraction are controlled.…read more