WHAT IS A STEM CELL?

Ultimately, every cell in the human body can be traced back to a fertilized egg that came into existence from the union of egg and sperm. But the body is made up of over 200 different types of cells, not just one.  All of these cell types come from  a pool  of stem cells in the early embryo. During early development, as well  as  later   in  life,  various
types of stem cells give rise to the  specialized  or  differentiat- ed cells that  carry out the spe- cific  functions   of  the   body, such  as  skin,  blood,   muscle, and nerve cells.

Over the past two decades, sci- entists have been gradually deci- phering  the processes by which
unspecialized  stem cells become the many  specialized  cell types in  the  body.   Stem  cells  can
regenerate  themselves or produce  specialized cell types. This property  makes  stem cells appealing  for scientists seeking to create medical treatments that replace lost or
damaged cells.