What are stem cells?

May 2005

When an egg is fertilised by a sperm to make a human embryo, that single fertilised egg cell divides millions of times to form the six billion or more cells that make up our bodies. Most of these cells have undergone a process that leads to them becoming specialised for a certain function.

Stem cells differ from other cells in three main ways:

• They have not developed into cells that perform a specific function.
• They are able to divide and produce copies of themselves.
• They can divide and produce cells that have the potential to become other, more specialised cell types or tissues.

Researchers are investigating three main types of stem cells for their potential use in medicine. In the human:

• Embryonic stem cells come from a four to seven-day-old embryo. They have the ability to form virtually any type of cell found in the human body but are not capable of developing into a whole new organism.
• Embryonic germ cells are derived from the part of a human embryo or foetus that will ultimately produce eggs or sperm.
• Adult stem cells have a more restricted ability to produce different cell types and to self-renew.

Source: Australian Stem Cell Centre

Action: For information on stem cells and the Monash Immunology and Stem Cell Laboratories, go to the Monash Immunology and Stem Cell Laboratories website.