Embryo development in mammals

• Zygote


  The fertilised egg
• Is the zygote totipotent or pluripotent?

  Totipotent
• Totipotent


  Able to develop into any cell type
• What is the first stage of embryo development known as?

  Cleavage
• Cleavage


  • A variation of mitosis involving repeated cell division but no interphase (so cell is dividing but not growing)
  • Happens as embryo moves down oviduct
• What is the result of cleavage?

  A blastocyst
• Blastocyst


  A hollow ball of small, identical, undifferentiated cells
• When does the blastocyst form?

  As the zygote enters the oviduct (approximately 5 days after fertilisation)
• What type of stem cell are cells of the human embryo?

  Embryonic stem cells
• Embryonic stem cells


  Cells that have the potential to differentiate into many cell types
• Are embryonic stem cells totipotent or pluripotent?

  Pluripotent
• Pluripotent


  Able to develop into many cell types
• How do the outer and inner layers of the blastocyst differentiate?

  • Outer layer of cells forms the placenta
  • Inner layer of cells have lost some ability to differentiate
• How does the blastocyst hatch?

  Inner layer breaks free of outer layer and begins to implant in uterus lining after approximately 7 days
• Cell determination


  The predestination of cells to become particular types from early in the development of the embryo (cells are destined to become a particular type just days after conception)
• Differentiation


  To develop into specific types