Focus on plant cells
(a) An environmental scanning electron microscope image of fresh onion cells under strain. The fracture causes the cell at n to explode, although the break is obscured by the ruptured cell's contents. The fracture (indicated by the arrow) then begins to propagate across the intact and turgid cell that is highlighted by the cross.
(b) Onion cells that have been treated with a chemical to destroy cell adhesion. The failure is intercellular and neighbouring cells readily separate.