stem cells

• Stem cells


  Cells that have not undergone differentiation
• Undifferentiated cell


  A cell which has not yet become specialised
• Embryo development


  1. Fertilised egg

  2. Early stages of embryo development

  3. Stem cells
• Embryonic stem cells


  Stem cells removed from the embryo that will differentiate into any cell type
• Adult stem cells


  Stem cells that remain in the bodies of adults, found in limited numbers at certain locations
• Locations of adult stem cells

  • Brain
  • Eyes
  • Blood
  • Heart
  • Liver
  • Bone marrow
  • Skin
  • Muscle
• Adult stem cells


  • Can differentiate into related cell types only, e.g. bone marrow cells can differentiate into blood cells and cells of the immune system but not other cell types
• Meristem


  Regions in plants where cell division occurs
• Cells of the meristem can differentiate to produce all types of plant cells at any time during the life of the plant</b>
• Main meristems in plants


  • Close to the tip of the shoot
  • Close to the tip of the root
• Cell differentiation in a growing shoot

  1. New cells produced continuously near the tip

  2. Cells become older and further away from the tip

  3. Cells become differentiated, enlarge and develop vacuoles