Recent EM and biochemical evidence indicates the primary component of LBs are abnormally phosphorylated neurofilaments that form a non-membrane bounded compacted skein in the neuronal soma.
Extracellular LBs occur following neuronal cell death and disintegration.
The cytoplasmic inclusions are generally circular, may indent the nucleus, and lack a distinct halo. CLBs display weak, variable or no affinity for silver stains. Identification is aided by using ubiquitin immunohistochemistry , shown in the top panel as darker densities than the surrounding cytoplasm.