Axons are normally elastic, but when rapidly stretched they become brittle, and the axonal cytoskeleton can be broken. Misalignment of cytoskeletal elements after stretch injury can lead to tearing of the axon and death of the neuron. Axonal transport continues up to the point of the break in the cytoskeleton, but no further, leading to a buildup of transport products and local swelling at that point.[25] When it becomes large enough, swelling can tear the axon at the site of the break in the cytoskeleton, causing it to draw back toward the cell body and form a bulb.[2] This bulb is called a retraction ball, the hallmark of diffuse axonal injury.[3]