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 differentiated
cells that carry out the specific
functions of the body,
such as skin, blood, muscle,
and nerve cells.
Over the past two decades, scientists
have been gradually deciphering
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.
This Web page is based on
Understanding Stem Cells: An Overview of the Science and Issues from the National Academies.
