movements

• Invagination


  Infolding of cell sheet into embryo

  
• Inturning of cell sheet over the basal surface of an outer layer

  Involution

  
• Migration of individual cells into the embryo

  ingression

  
• The expansion of one cell sheet over other cells

  Epiboly

  
• Splitting or mirgration of one sheet into twoo sheets

  Delamination