Intradural Portion Research Articles

The ventriculus terminalis and filum terminale of the human spinal cord

Serial sections of the conus medullaris and the filum terminale of 23 randomly selected human spinal cords were studied by light and electron microscopy, and following immunoperoxidase staining for glial fibrillary acidic protein (GFAP), vimentin, neuron-specific enolase (NSE), amyloid β protein, and S-100 protein. The intradural portion of the filum contains bundles of GFAP-positive glial fibers, scattered silver- and NSE-positive neurons, segments of peripheral nerve, blood vessels, fibrous connective tissue, and fat. Glial cell clusters varying from five to 100 cell layers thick at times constitute the bulk of the filum. The periependymal glial cells possess moderate amounts of eosinophilic cytoplasm and relatively uniform round to ovoid nuclei containing evenly distributed chromatin. They are distributed diffusely with no specific pattern of organization, although some of them showed a tendency to form acinar structures. A minority of the glial cells showed GFAP immunoreactivity, and some were immunoreactive for vimentin. Electron microscopy demonstrated the presence of periependymal cells showing cilia, microvilli, and the formation of intercellular junctional complexes, as well as cells containing bundles of glial filaments within the cytoplasm. Degenerated NSE-positive neurons and degenerated neurites resembling neuritic plaques were also demonstrated. However, immunoperoxidase staining for amyloid β protein was negative in these structures. Thus, the filum terminale is endowed with an abundance of glial cells and neurons and is not simply a fibrovascular tag. Periependymal glial cells in the filum terminale should not be mistaken for neoplasm. The presence of neuropil with profuse astroglial and neuronal components within the filum terminale suggests a possible functional role for these structures.

Scanning Electron Microscopy and Immunoglobulins of the Endolymphatic Sac in Meniere's Disease

SEM and immunoglobulin staining of the intradural portion of the endolymphatic sac (ES) were investigated. All 15 normal subjects, from fetuses to an 80-year-old adult, showed well arranged epithelial cells. In Menière's disease (all 15 patients) the ES showed various types degeneration of the epithelial cells. Inner ear deafness experimentally produced by kanamycin injection showed a similar degeneration of the ES. IgG of the ES in Menière's disease showed moderately evident deposits compared with normal subjects. However, these findings were also found to the same degree as IgG deposits in animal deafness produced by KM injection. From the above results it can reasonably be concluded that the degenerated findings of the ES and deposits of the IgG in Menière's disease may possibly be the result of cochlear deafness.

Scanning Electron Microscopy and Immunoglobulins of the Endolymphatic Sac in Normal Human Subjects and Sensorineural Deafness

The pathophysiology of the endolymphatic sac (ES) in Meniere's disease was studied by scanning electron microscopy and staining of immunoglobulins in the intradural portion of the ES. The peroxidase-antiperoxidase method by means of paraffin sections was used for staining of immunoglobulins. First, subjects without hearing impairment and malformation of the temporal bone, ranging from a 7-month-old fetus to an 80-year-old adult, were investigated. All subjects, including fetuses, showed well-arranged epithelial cells by scanning electron microscopy. The epithelial cells in the proximal portion of the intradural ES were oval, showing a tendency of transitional change to be flat as they drew near the distal portion of the ES. The epithelial cells consisted mostly of light cells, but sporadic dark cells were seen. Regarding the immunoglobulins. IgG was slightly positive in the epithelial and subepithelial layers. All 15 patients with Meniere's disease showed various types of degeneration of the epithelial cells though to varying degrees. However, these findings were also seen in cases of cochlear deafness. On the other hand, the ES of acoustic tumors, with retrocochlear or neural deafness revealed a normal finding, as found in healthy subjects. Inner ear deafness experimentally produced in animals by Kanamycin sulfate (KM) injection showed degeneration of the epithelial cells of the ES similar to that found in human cochlear deafness. IgG of the ES in Meniere's disease showed moderately evident deposits compared to normal subjects. However, this was also found not only in inner ear deafness other than Meniere's disease, but also in animal deafness experimentally produced by KM injection. It is very interesting to note that moderate endolymphatic hydrops was found in animals one year after Preyer's reflex had disappeared. It is postulated that endolymphatic hydrops develop because of impairment of endolymphatic fluid resorption at the rugose portion and stenosis of the lumen in the same portion, due to degeneration of the epithelial cells. From the above results, it is argued that degenerated epithelial cells and immunoglobulins of the ES in Meniere's disease may arise from the sequelae of cochlear deafness. It is also hypothesized that endolymphatic hydrops--at least in the terminal stage of Meniere's disease--may be consistent with the same pathophysiological conditions as in animal experiments.