Axonal spheroids are bubble-like biological features that form on most degenerating axons. During neurodegeneration, bubble-like swellings form along the length of the axon, a primary and early effect of dynamic axonal deformation. These varicosities, spheroids, or swellings have been described as beads on a string and branches bearing fruit, and they frequently appear on degenerating axons. The focal swellings on degenerating axons, axonal spheroids, are often filled with cellular debris such as organelles, pathological proteins, and disorganized cytoskeletal elements. [from
HPO]