What are stem cells ?
Tissues and organs in the body are made of specialised cells that assure their specific functions. Maintenance and repair of these tissues and organs depend upon resident unspecialised adult stem cells. They are still at an early stage of development and retain the potential to turn into the different types of cells of that tissue or organ.
In bones, some typical adult stem cells, the bone marrow stem cells, give rise to all kinds of blood cells. Apart from those of the blood cell lineage, other stem cells are found in the bone, which are able to mature into cells specific to bone, cartilage, fat, tendons, muscle and heart.
During pregnancy, cells from bone marrow of the developing foetus find their way into the umbilical cord and placenta. Research suggests that umbilical cord blood stem cells, less mature than those from adult bone marrow, might be induced to turn into non-blood cells.
The only cells that can evolve into any cells in the body are found in few day-old fertilised eggs, and are called embryonic stem cells.