Virus-like particles in human vestibular ganglion cells.

We found intracytoplasmic aggregates of virus-like particles in human vestibular ganglion cells. These particles were always observed in the peripheral area of the cytoplasm. Morphological characteristics of the cytoplasm are similar to those of other ganglion cells. The inclusion bodies are round and measure about 1.7 micron in maximum diameter. They consist of a porous convoluted dense material and virus-like particles. The overall diameter of 118 randomly selected particles varies from 36 nm to 73 nm, and the mean value is 53 nm. Most of the particles are spherical while a few possess a hexagonal or semicircular profile. The particles exhibit a double external membrane or vesiculated external layer. Most of the particles are empty. There are, however, some particles which show vesicular structures in their content. Although our present data are insufficient to determine these particles as viral, their hexagonal shape and size are similar to true virus. With these data in mind, we suggest that these particles might be a dormant form of virus and may possibly produce infectious disease in the inner ear.