Haruhiko Masutani

Noise-induced Vasoconstriction in the Cochlea

Observation of the inner ear vessel using the casting method has the advantage of revealing the whole of the blood vessel in the one animal. This study was employed the blood vessel casting method and stylene cracking method to observe the morphological changes occurring in the inner ear vessel due to sound exposure. Results indicated vasoconstriction of the blood vessels of the cochlear lateral wall and spiral lamina due to sound exposure. Sludging of the blood cells was also recognized in these blood vessels. Such morphological changes were found to be reversible. The above findings thus imply that the cause of NITTS (Noise-Induced Temporary Threshold Shift) and NIPTS (Noise-Induced Permanent Threshold Shift) lies in impaired blood flow due to vasoconstriction of the inner ear capillary.

Microvascular Structure of the Larynx A Scanning Electron Microscopic Study of Microcorrosion Casts

In this study, scanning electron microscopic observations were made of the microvasculature of the larynx of guinea pigs, rabbits and humans. The results showed that 1) The epiglottis being the most abundant of all laryngeal structures in vascular plexus, with some of the vessels perforating cartilage; 2) Blood vessels of the vocal cord course along its long axis showing undulation; arteriovenous anastomoses was noted; 3) In the arytenoid, blood vessels were found to be irregularly coursing and tortuous, thereby facilitating the purpose of smooth movements of this structure.

Enhancement of Ciliary Action by a β-Adrenergic Stimulant

It is known that β-adrenergic stimulants enhance mucociliary transport in the respiratory tract. The present study clearly indicated that such an enhancement resulted from not only the alteration in secretory function but also the direct stimulation of ciliated cells. However, the enhancement of ciliary beating depended on the morphological changes in ciliated cells. On the other hand, the effect of terbutaline aerosol, a β-adrenergic stimulant, on patients with chronic sinusitis was evaluated by paranasal sinus radiography. Consequently, marked improvements in shadows were achieved after 4 weeks in 40% of the cases examined.

The Ciliary Activity of the Middle Ear Lining in Some Pathological States

The ciliary activity in some pathological middle ear lining was discussed with special reference to the morphology of the epithelial cells in this paper. The changes in ciliary activity due to in vitro Staphylococcus aureus injection did not practically show any differences between the sites. On the other hand, the time-course changes in ciliary activity after in vivo S. aureus injection were found to differ between the sites. Ciliary activity was rather accelerated at the proximal site, while it was decelerated at the distal site. Few changes but for sporadic small compound cilia were observed at the proximal site, and some inflammatory changes were noted at the epithelium of the distal site. SO2 exposure affected the middle ear lining of rabbits. Fourteen days after 4 weeks exposure to SO2, the middle ear lining displayed declined ciliary activity and many signs suggestive of secretory asthenia. In addition, the middle ear lining of rabbits given about 600 mg carbocysteine, both during and 2 weeks after the exposure displayed excellent ciliary activity and normal morphology of the epithelial structure.

Observation of the Otolithic Membrane by Low-Vacuum Scanning Electron Microscopy

Untreated specimens (i.e. not fixed, dehydrated or embedded) of the otolithic membrane from the sacculus of guinea pigs were observed at the ultrastructural level by low-vacuum scanning electron microscopy (LVSEM). This technique revealed the presence of a 15- to 20-mu m-thick layer of an amorphous substance (the supraotolithic cupula zone) on the surface of the otoliths, which was not detectable by conventional methods. Elemental analysis of this substance revealed relatively high concentrations of oxygen, sodium, phosphorus, chlorine, potassium and calcium. This amorphous substance was thought to have a role in fixing the otoliths onto the sensory epithelium. In addition, the tips of the triangular portions of the otoliths were not sharp as shown by conventional SEM and were seen to be more rounded by LVSEM.

Microvascular disorder of the stria vascularis in endolymphatic hydrops.

To investigate the role of pathology of the stria vascularis in endolymphatic hydrops, the vascularity and atrophy of the stria were examined by histological observation in guinea pig temporal bones affected by experimental endolymphatic hydrops. Blood cell sludge and vasoconstriction accompanied by strial atrophy were observed in the coiled arteriole and capillary of the stria vascularis of the ear with endolymphatic hydrops after exposure to noise, suggesting the development of inner ear circulatory disturbance. Furthermore, these findings were observed around the upper turn of the cochlea. The effect of glycerol and difenidol hydrochloride on endolymphatic hydrops was also examined. Vasoconstriction and blood cell sludge disappeared following administration of these agents, accompanied by collapse. These findings suggest the possibility that the circulatory disturbance might be the cause of endolymphatic hydrops, followed by strial atrophy.

Measurement of Inner Ear Vessel Diameters with Casting Method

Under scanning electron microscopy we measured the vessel diameters of every part of the inner ear in rats and guinea pigs with casting method using Mercox resin. There were only few errors in measurement values in the same part of the same vessel with this method. The vessels of the stria vascularis were much larger in diameter than any other capillaries in the lateral wall of the cochlea in the rat and especially in the guinea pig. It is suggested that the velocity of the blood flow in the stria vascularis is slow and that the stria vascularis can retain much blood. The anterior vestibular artery (AVA) was larger in diameter than the posterior vestibular artery (PVA). The AVA supplies the large area in the vestibule whereas the PVA supplies the small area.

Development of Inner Ear Vessels A Scanning Electron Microscopic Study

The development of the inner ear vessels of guinea pigs were studied by SEM. Employing 32- to 55-gestational-day-old guinea pig embryos, corrosion casts of inner ear blood vessels were prepared using Mercox resin and then observed by scanning electron microscopy. Between the 35th and 40th gestational days, the vascular structure of the vestibule was sufficiently developed, but the capillary network in the wall of the cochlea remained immature. Thus, in the guinea pig, the development of the vestibular structure precedes the development of the cochlear vessels. Moreover, at both sites, the density of the embryonic blood vessels was high, and the vessels were believed to transport a large blood flow. From about the 40th day of gestation, the coiled vessels and the capillary network in the lateral wall of the cochlea underwent rapid development, and the vascular structure in both the vestibule and cochlea was nearly complete by the time of birth.

Distribution of arteries from brain stem to inner ear around the internal auditory canal.

In the present work, casts of vessels surrounding the internal auditory canal of the guinea pig were subjected to scanning electron microscopic examination. Most casts were prepared by the resin-casting method using Mercox resin. The following results were obtained: 1) Individual variations and bilateral asymmetry were observed in the anterior inferior cerebellar artery (AICA), which branches off the basilar artery (BA); 2) Frequently a loop the AICA was found in the CP-angle and internal auditory canal; 3) The internal auditory artery (IAA) did not always originate in AICA but sometimes arose directly from BA; 4) In common cochlear artery and anterior vestibular artery, there were individual differences and asymmetric branching patterns on both sides; 5) We conclude that inner ear disease of vascular origin may be influenced by individual variations in the BA and its branches.

Blood-Flow Regulation in the Vestibulum and Inner Ear Microvasculature in Experimental Hydrops: A Scanning Electron Microscopic Study

Blood-flow regulation in the inner ear, particularly the cochlea, has been the subject of many studies reported so far, and the special characteristics of capillary plexuses and arteriovenous (AV) anastomoses in the stria vascularis and spiral ligament are well known. With regard to the vestibule, on the other hand, basic studies on blood flow regulation have been insufficient and incomplete, although reports are available on unique features of blood vessels. In some cases of dizziness due to vestibular disorder, circulatory disturbance of the vestibule has been implicated as the underlying cause and, in fact, circulatory agents are in common use in the treatment of the condition.