Neuroglial tissue in human eighth nerve specimens.

One hundred eighty nerve biopsy specimens from patients with eighth nerve tumors or other vertiginous diseases requiring vestibular neurectomy were studied. In many specimens light microscopy revealed pale areas among the myelinated nerve fibers in the neurolemmal portion of the eighth nerve. Electron microscopy showed that these were ectopic areas of glial tissue consisting of bundles of numerous cytoplasmic processes of fibrous astrocytes. The abundance of filaments within each process and the occurrence of microtubuli suggest that these processes are reactive astrocytes and accordingly are present as a consequence of the reparative potential of the astroglial tissue after a neuronal lesion. The possible functional significance of the findings is discussed.