stem cells

• Stem cells are unspecialised cells capable of self-renewal that have the ability to differentiate into distinct cell types
• There are two types of stem cells:

  • Embryonic Stem Cells
  • Adult Stem Cells
• Embryonic Stem Cells:

  • Undifferentiated cells of embryos from the blastocyst stage
  • They can be obtained from 3 to 5 day old embryos from IVF programs
  • They can become numerous types of cells and replicate indefinitely
• Adult Stem Cells:

  • Present in small numbers in some adult tissues like hair follicles, bone marrow and the spinal cord
  • They can only become a limited range of cells and cannot indefinitely reproduce
• Embryonic stem cell potency:

  • Totipotent - gives rise to any cell type
  • Pluripotent – give rise to any of the three germ layers. Blastocytes
• Adult stem cells:

  • Multipotent – give rise to multiple, but limited, cell types. Eg. bone marrow
  • Unipotent – give rise to only one cell type, but can divide repeatedly. Eg. skin cells