Ultrastructural alterations of the vestibular nuclei in Jacob-Creutzfeld disease. 
The morphological alterations of the vestibular nuclei in a case of Jacob-Creutzfeld disease were studied with light and electron microscope.  The most prominent histological findings were the neuronal degeneration and neuronal loss resulting in a marked decrease of the total population, the increased reactive astrocytosis which demonstrated an extensive perivascular arrangement, the microgliosis and the interstitial spongiosis.  At the ultrastructural level a marked dilatation of the astrocytic processes was seen.  Most of them were completely transformed to sizeable cysts which were divided by membranous structures into smaller spaces.  A large number of glycogen granules was accumulated into astrocytes and microglial cells.  The neurons demonstrated numerous alterations such as (a) large accumulation of lysosomes, (b) fragmentation of the microtubules, (c) dilatation of the cisternae of the smooth endoplasmic reticulum, (d) mitochondrial abnormalities, (e) tremendous loss of the dendritic spines, (f) dilatation of the axonal terminals, (g) decrease of the number of the synaptic vesicles in the presynaptic terminal, (h) dilatation of the synaptic cleft, (j) dilatation and lysosomal accumulation in the postsynaptic component, (k) numerous multivesicular bodies and coated vesicles in pre- and postsynaptic terminals.  In the neuropile space there were plenty of degenerated dendritic profiles.  The degeneration of the vestibular nuclei of the brain stem was more extensive than the degeneration of the nuclei of the other brain stem cranial nerves.