Recurrent lower gingival squamous cell carcinoma spreading along the pathway of the inferior alveolar nerve.

Computed tomography images showed recurrent lower gingival squamous cell carcinoma spreading from the mandibular foramen to the middle cranial fossa. This extensive tumor spread followed exactly the same anatomic pathway as the inferior alveolar nerve. Histopathologic examination revealed squamous cell carcinoma. Tumor spread was thought to be caused by perineural invasion. This case demonstrates computed tomography features of perineural tumor spread along the inferior alveolar nerve.

Anatomical and physiological characteristics of the vestibular ganglion of the bull frog.

The spatial distribution of nerve fibers from individual vestibular end organs in the vestibular ganglia (VG) was studied using horseradish peroxidase (HRP). HRP was injected into the cut end of the bull frog ampullary nerve. Stained neural elements were counted on the serial sections. Spatial distribution was also studied by recording ampullary nerve compound action potentials (AP) from VG. The anterior semicircular canal (SC) nerves were distributed in the anterior half of VG. The horizontal SC nerves were also distributed in the anterior half of VG, but tended to be posterior. The posterior SC nerves were found predominantly in the posterior half and antero-dorsal portions. These distribution patterns corresponded well with those confirmed by AP recording. There were a few neural connections between anterior and posterior SC, or horizontal and posterior SC, indicating receptor-receptor fibers.

Effect of gentamicin on vestibular ganglion.

The morphological changes of the vestibular ganglion induced by gentamicin (GM) were investigated using light, scanning and transmission electron microscopy. The guinea pigs were injected 4 mg of GM into the middle ear for 5 days. The vestibular ganglion was observed up to 4 weeks after the treatment. Three days after the treatment the degenerative change was first noted in the vestibular ganglion. The degenerative process started from the destruction of mitochondrial cristae and vacuolization of the cytoplasm of the Schwann cell. The cytoplasmic organelles in the ganglion cell gradually deteriorated with swelling of the endoplasmic cisterns as well as Golgi apparatus. At the later stage, the myelin sheath around the ganglion cell disappeared and the number of the cells reduced. These changes of the ganglion cell may be due to the direct action of GM.

Three-dimensional observation of the spiral ganglion cell. Normal structure and pathological changes.

Spiral ganglia of guinea pig and mouse were investigated by scanning electron microscopy (SEM). The cochlea was freeze-fractured and then macerated with 0.1% OsO4 solution for 70-90 h (A-O-D-O method (1]. This allowed three-dimensional observation of the general view of the spiral ganglion and the intracellular structure. Two types of spiral ganglion cell, type I and type II, could be distinguished by the A-O-D-O method. Intracellular membranous structures such as mitochondria, endoplasmic reticulum (ER) and Golgi apparatus were also demonstrated stereoscopically. Furthermore, morphological changes in mouse spiral ganglion cells due to injection of Mycobacterium fortuitum were observed, using SEM. The degenerative process began as swelling of the mitochondria. When Schwann cell became affected, the myelin sheath disappeared and the ganglion cell border became indistinct. This degeneration developed rapidly, suggesting a direct influence of the bacteria on the ganglion cell. Various types of inclusion body with limiting membrane could be demonstrated stereoscopically. As Romand & Romand (4) suggested, these inclusion bodies may be remnants of cellular organellae or various type of lysosomes.

Morphological study of the cells in the planum semilunatum.

The fine structures of the epithelial cells in the planum semilunatum were investigated using scanning and transmission electron microscopy. The chicks and guinea pigs were used for this study. In both guinea pig and chick, the body of the planum semilunatum cell was cylindrical. Its length decreased towards the utricular and canal side, resulting in cuboid-shaped cells. In the guinea pig, the flat surfaced hexagonal cells with few microvilli were arranged like flagstones over the whole area of the planum semilunatum, while in the chick the cells with many prominent microvilli were found on both sides of the crista. The cytoplasm contained well developed endoplasmic reticula and abundant granules. Interdigitations between the neighbouring cells were well developed. Basement membrane was slightly folded but no basal infolding was observed. The morphological characteristics of the planum semilunatum cell highly suggest that these cells have some secreting function.

[Clinical study on the effect of adjuvant immunochemotherapy using OK-432 and 5-FU in pharyngeal and laryngeal cancers].

A randomized controlled trial was carried out on 38 pharyngeal and 59 laryngeal previously untreated cancers to evaluate the effects of adjuvant immunochemotherapy using 5-FU with and without OK-432. After each fundamental therapy, 5-FU was given orally at a dose of 200-300 mg/day for more than a year. OK-432 was intracutaneously administered at a dose of 5KE once a week for more than a year. Three-year survival rates and disease-free intervals were estimated for the two groups. In cases of pharyngeal cancer, the 3-year survival rate was 58% in both groups and the disease-free interval rates for up to 3 years after the fundamental therapy was 49% in the OK-432 + 5-FU group and 52% in the 5-FU group. These results showed no statistically significant difference. In laryngeal cancers, the 3-year survival rate was 96% in the OK-432 + 5-FU group and 82% in the 5-FU group. These results also showed no statistically significant difference. The disease-free interval rates were 87% in the OK-432 + 5-FU group and 64% in the 5-FU group, revealing a statistically significant difference (p less than 0.1). This suggests that OK-432 is more effective in producing a higher survival rate in cases of laryngeal cancer.

The morphological changes in the vestibular sensory epithelia following electrical stimulation.

The morphological changes of the vestibular sensory epithelia of the guinea pig following electrical stimulation were investigated using scanning electron microscope. Positive and negative square wave pulse stimulation was given through a silver ball electrode placed on the round window membrane for one hour. The current intensities used were 100, 200 and 300 microA. While the direct current stimulation at intensities of 100 or 200 microA did not cause any significant changes, severe damage of the utricular macula and the ampullar crista of the lateral semicircular canal was observed at 300 microA. The degenerative changes such as fusion of sensory hairs, protrusion of the cuticular plate and loss of sensory cells were found on both the utricle and the semicircular canal. In the most severely damaged area, the sensory epithelial surface was badly torn apart. In the clinical application of direct current to the inner ear for relieving tinnitus, special attention should be paid to the vestibular organ.

Morphological changes in the vestibular epithelia and ganglion induced by ototoxic drug.

The morphological changes of the vestibular sensory epithelia and the vestibular ganglions induced by Gentamicin(GM) were investigated using scanning electron microscope, transmission electron microscope and light microscope. The guinea pigs were injected with a single application of 4 mg (0.1ml) of GM into the middle ear through the tympanic membrane. The vestibular organs and the ganglions were observed up to 6 months after the treatment. Four days after the injection, fused, ballooned and missing cilia were observed in the vestibular sensory epithelia. These changes progressed and extended toward the periphery of the crista and the macula. The changes of the vestibular ganglions were first observed one month after the treatment. The degenerative process started from destruction of the mitochondrial cristae and vacuolization of the cytoplasm in the Schwann cell. The next step of the change was dissociation of the myelin sheath around the ganglion cell. The cytoplasmic organelles in the ganglion cell gradually deteriorated. At the later stage, the myelin sheath around the ganglion cell disappeared and the number of the cell reduced. Furthermore, the myelin sheath of the nerve fiber was dissociated. In this study the signs of the vestibular ganglion damage were later than that of the vestibular organ. However, we thought the changes in the ganglion are probably due to direct influence of GM, since the degeneration was found to develop in a relatively short period.

Three-dimensional observation of the cochlea. Intracellular structure of the hair cell and the supporting cell.

Intracellular structures of the guinea pig cochlea were observed by scanning electron-microscopy. The cochlea was freeze-fractured and then macerated with 0.1% OsO4 solution (aldehyde-osmium-DMSO-osmium (AODO) method). Intracellular organelles, such as mitochondria, endoplasmic reticulum (ER), and Golgi apparatus, were demonstrated stereoscopically. The ER of the outer hair cell showed the most interesting features, such as subsurface cisternae and lamellar body. The subsurface cisternae which formed a stratiform network covered the inner surface of the cell membrane of the supranuclear part. Variously shaped mitochondria were found on the innermost layer of the subsurface cisternae. The lamellar body consisted of dilated cisternae and tubules of ER. The tubular ER of the lamellar body were contiguous with the subsurface cisternae. The pillar cells, Deiters' cells and Hensen's cells had well-developed tubular ER, while Claudius' cells had poorly developed tubular ER.

Electron-microscopic study of the vestibular dark cells in the crista ampullaris of the guinea pig.

The ultrastructure of the vestibular dark cells in the crista ampullaris of the guinea pig was observed using both transmission and scanning electron microscopy. The dark cells had numerous vacuoles of varying size and electron density, and also characteristic well-developed basal infoldings. These findings strongly suggest that the dark cells play an important role in fluid transport. Unique meshwork structures were observed on the luminal surface of the dark cells. Otoconia showing varying degree of degeneration were occasionally recognized on and near these structures. Electron microscopy revealed that the meshwork was comprised of cytoplasmic processes in a reticular arrangement. They seem to be engaged in the metabolism of otoconia, and perhaps also in fluid transport.

Development of the crista ampullaris in the mouse.

The process of development of the crista ampullaris has been investigated in the mouse using SEM. Cristae ampullaris of the CBA/CBA mice, from the 13.5th gestational day to the day 2 weeks by were studied. On the 13.5th gestational day, there were numerous microvilli and a primary cilium on the crista ampullaris. Sensory hairs first appeared on the 14.5th gestational day. The kinocilium and stereocilia were short and the length of the stereocilia was almost constant. The formation of the cupula, which had fine network-like structures, started on the 14.5th gestational day.

[Experimental study of the ototoxicity of fosfomycin].

Two tenths ml of 5% fosfomycin sodium solution (10 mg) was injected into the tympanic cavity of guinea pigs once a day for 7 days. Auditory brain stem response (ABR) was performed to examine the effect of the drug on the experimental animals. Additionally, a scanning electron microscopic study was also performed to observe the effect of the drug on outer hair cells of the organ of Corti and on vestibular sensory epithelia. No degenerative changes were observed in outer hair cell cilia of the organ of Corti and the vestibular sensory cilia at 1 day, 7 days, 14 days and 1 month after injection. No changes of the threshold of ABR were also noticed.

Scanning electron microscopic observation of the crista ampullaris.

The crista ampullaris of the guinea pig and the bull frog were investigated by scanning electron microscopy. The crista ampullaris were freeze fractured or sheared followed by maceration with 0.1% OsO4 solution. Following this, three-dimensional intracellular structures were observed. The mitochondria of the sensory cells varied in shape from globular to long and slender. Golgi apparatus and endoplasmic reticulum of the sensory cells were also demonstrated clearly. Nerve elements, nerve endings and synaptic structures were also observed stereoscopically.

Inner ear damage induced by Mycobacterium fortuitum.

We used electron microscopy to investigate Mycobacterium fortuitum-induced changes in the inner ears of mice. We found that the inner and outer hair cells had degenerated and disappeared in the organ of Corti. Changes in the lower turn of the cochlea were more severe than those of the upper turn while the changes of the outer hair cells were more severe than those of the inner hair cells. Disappearance, fusion and ballooning of the sensory hairs were observed in the vestibular organs. The bacterial extract also induced inner ear damage which was similar to that caused by live M. fortuitum.

Intracellular structure of the outer hair cell of the organ of Corti.

The intracellular structure of the outer hair cells of the normal guinea pig organ of Corti was investigated three dimensionally by scanning electron microscope. Freeze fracturing technique followed by maceration with a 0.1% OsO4 solution (osmic maceration method) was used. Among the cell organelles, the endoplasmic reticulum (ER) showed the most interesting features, such as subsurface cisternae and lamellar bodies. The subsurface cisterna which formed a stratiform network covered the inner surface of the cell membrane and the stratiform structure disappeared at the infranuclear region. Variously shaped mitochondria (spherical, cylindrical and branched) were found on the innermost layer of the subsurface cisterna. The lamellar body which was located beneath the cuticular plate consisted of dilated cisternae and tubular ER and was surrounded by mitochondria. The tubular ER of the lamellar body were continuous with the subsurface cisterna.

Three-dimensional structures of the vestibular sensory epithelia.

Vestibular neurosensory epithelia of the guinea pig and the bull frog were investigated by scanning electron microscopy. The crista ampullaris or macula were freeze fractured followed by maceration with 0.1% OsO4 solution for 24-60 h (osmium-DMSO-osmium method). Following this, three-dimensional intracellular structures were observed. The mitochondria which exist in the nerve chalice surrounding the type I cell were various in shape, globular, long and slender. Golgi apparatus, endoplasmic reticulum and thin fibrous structures of the sensory cells or supporting cells were clearly demonstrated. Concerning nervous system, nerve fibre, afferent and efferent nerve endings, further synaptic structures were also observed stereoscopically.