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Types of stem cells: From embryos to adults
Published on 04/25/2005
Page 1

Not all stem cells are created equal. The potential for stem cells to differentiate into other specialized cells changes as an embryo develops. Stem cells can be:

Totipotent. In the
early stages after fertilization — immediately after a sperm and egg
join together and begin dividing — stem cells are considered
totipotent. This means that these cells can form any type of cell, including those cells necessary for an embryo to develop into a human, such as placenta cells.

  • Pluripotent.
    Several days after conception, as an embryo begins to develop, its stem
    cells become pluripotent. Such cells can form any kind of cell found in
    adults, making them very versatile. Unlike totipotent stem cells,
    however, they can't become cells necessary for an embryo to develop
    into a human. Cells with similar properties are also found in fetal
    tissue.
  • Multipotent.
    Eventually, pluripotent stem cells become multipotent stem cells — the
    type found in adults. Multipotent stem cells can no longer develop into
    all or most cell types. Instead, they can develop into certain cell
    types within a specific tissue, organ or system. For example, bone
    marrow stem cells can develop into all types of blood cells, which are
    normally produced by your bone marrow, as well as bone, cartilage and
    fat cells. Stem cells in your brain can turn into nerve cells and other
    types of brain cells.

    Multipotent stem cells exist in certain
    tissues and organs throughout your body, including your brain, blood
    vessels, liver, muscles and bone marrow. Researchers believe that
    multipotent cells remain — undivided — in these parts until they're
    called into duty to create necessary new cells, such as after a disease
    or injury.

    Some scientists suspect that stem cells in one body part may be able to form cells used in other body parts, a quality called plasticity.
    For example, a stem cell in your bone marrow that makes blood cells
    might also be able to make heart-muscle cells or liver cells.


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