[Clinical characteristics of different cordectomy types with potassium titanium phosphate laser].

OBJECTIVE: To study the clinical characteristics of different potassium titanium phosphate(KTP) laser types and surgical the recuperating course of cordectomy under suspension laryngoscope. METHOD: Follow-up observation were applied on 76 patients with cordectomy. Restoration of laryngeal structure and change of the quality of voice were observed and recorded. RESULTS: Type 1, normal laryngeal structure and function were restored postoperatively after 3 months; Type 2, a fold like vocal cord (new vocal cord) appeared 3 months later. Laryngeal structure was basically restored; Type 3, a mucosal fold appeared postoperatively after 6 months in most patients, but it lost motion function. Recurrence time was mainly found 2-4 months. Recurrence rate was 6.7%. Two and 5-year survival rate were 100%. CONCLUSIONS: Cordectomy with KTP laser can result in good effect and less injury. Type 2, 3 can retain thyroarytenoid muscle as much as possible on the basis of radical cure.

[Clinical study on treatment of early glottic carcinoma with different cordectomy].

OBJECTIVE: To explore the advantage of KTP laser cordectomy in the treatment of early glottic carcinoma. METHOD: Follow-up observation on 30 patients who had KTP laser cordectomy and 18 patients who had laryneal split cordectomy was applied, then their postoperative laryngeal structure's change, the quality of voice and the quality of life (QOL) were compared and analyzed. RESULT: The patient group treated by KTP laser grew out a piece of new cord just at the place where it was excised after half a year, and the quality of voice was obviously improved near to norm, and they had higher QOL. On the contrary, the other group had no newly grown cord, their quality of voice was better in the first half year but was worse last out. Their QOL was lower than the laser group before decannulation and the same as the laser group after the decannulation. There are 2 cases recurrented in the laser group and 1 case recurrented in the laryneal split group, the two groups all had no metastasis and death in laryneal carcinoma by 2-4 years follow up postoperation. CONCLUSION: On the basis of effecting radical cure, the early glottic carcinoma treated with non-contact KTP laser with suspension laryngoscope can result in good recuperating in laryngeal structure, less injury and high QOL. So it makes micro-injury treatment in laryngeal carcinoma come true and better than the laryngeal split cordectomy.

[Multiple primary cancers of oral cavity and pharynx].

Multiple primary cancers were found in 23 of 68 patients (34%) with an index cancer in the oral cavity or pharyngeal area treated in our institute from June 1995 to July 1998. Four cases had triple primary cancers. All 68 cases underwent upper and lower gastrointestinal endoscopy as well as ultrasonography of the liver. Lung CT was performed in cases with abnormal findings on chest roentgenograms. Multiple cancers were found in 5 of 25 oral cavity cases (20%), 6 of 14 mesopharynx cases (43%) and 12 of 29 hypopharynx cases (41%). Nine of 23 cases (39%) were synchronous and 14 (61%) were metachronous. Eighteen of 27 (69%) secondary cancers occurred in the upper aerodigestive tract with an especially high incidence (22%) in the esophagus. Gastroendoscopy also revealed 7 neoplastic lesions, aside from cancers, with the total abnormal rate of 24% (24/68). Thus, gastroendoscopy is useful for the diagnosis of multiple primary cancers. The frequency of multiple primary cancers in males (33%) was not different from that in females (35%). The average age of multiple primary cancer patients (65.1 years) was a little higher than that of single cancer patient (62.7 years). Smoking or drinking was not related to the incidence of multiple cancers. The interval between the first and the second cancer in metachronous cancer cases was 25.5 months on average, and within 4 years in 71% (10/14) of the cases. This result suggests that close follow-up including endoscopy should be required for at least 4 years after treatment of oral or pharyngeal cancer. Radical treatment for each of the multiple cancer lesions was performed in 22 of 23 cases, and the mortality rate of multiple primary cancer cases was not significantly different from that of single cancer cases. Among 7 cases who died of disease, 5 cases died of distant metastasis, suggesting that control of distant metastasis is an important issue in the treatment of multiple primary cancers.

Expression of connexin 26 and Na,K-ATPase in the developing mouse cochlear lateral wall: functional implications.

The immunohistochemical localization of connexin 26 (a gap junction protein) and Na,K-ATPase in the mouse cochlear lateral wall was studied at different ages between 0 and 30 days after birth (DAB). Connexin 26-like immunoreactivity was sparsely distributed among the connective tissue cells just lateral to the future marginal cells of the stria vascularis on 0 DAB. In the mice of 3-6 DAB, connexin 26 was observed in the strial basal cell area, and was increased in its distribution density on 10 DAB. Connexin 26 was sparsely distributed among the fibrocytes in the spiral ligament and the suprastrial zone on 10 DAB, and its distribution density increased rapidly in the mouse on 12 DAB. The immunohistochemical distribution reached the adult pattern in the cochlear lateral wall on 15 DAB. Weak Na, K-ATPase-like immunoreactivity was observed in the epithelial cells, corresponding to the future strial marginal cells, on 0 DAB. Its staining intensity was enhanced with the increase of age, and reached the adult pattern on 10 DAB. In contrast, Na,K-ATPase-like immunoreactivity in the type II fibrocytes and suprastrial fibrocytes was first detected on 12 DAB, and reached the mature level on 15 DAB. It is well known that the endolymphatic potential (EP) reaches the adult level 2 weeks after birth. The expression patterns of connexin 26 and Na,K-ATPase in the fibrocytes of the spiral ligament and the suprastrial zone coincided with the rapid growth and maturation of EP. These findings may suggest a role for the gap junctional communications and Na,K-ATPase activity of the fibrocytes within the cochlear lateral wall in the generation and maturation of EP.

[Simultaneous reconstruction of pharyngoesophagus and phonetic shunt following laryngopharyngoesophagectomy].

Because of its many advantages, free jejunal transfer has gained wide acceptance for pharyngoesophageal reconstruction after ablative surgery. Because the jejunum is well vascularized, it facilitates good wound healing, and has a low incidence of anastomotic insufficiency, fistula formation and stricture. However, voice rehabilitation in this group of patients can be difficult. Therefore, we performed primary tracheojejunal shunt operations for voice restoration with jejunum siphons using Nozaki's method (type 3). In this procedure, after dividing a section of the jejunum into two segments, the reconstructed neopharyngoesophagus is anastomosed in a side-to-end fashion to the fabricated shunt using the other segment of the jejunum, as an "elephant nose shunt" so called because of its appearance. Voice restoration can be achieved in patients who undergo laryngopharyngoesophagectomy through these reconstructive procedures. We performed this surgery for nine hypopharyngeal cancer patients after total pharyngo-laryngo-esophagectomy. Following placement of the shunt, no special care was required. Only one patient developed a severe aspiration. No leakage was seen and the swallowing function was preserved in all patients. Four of nine patients could speak well following these procedures. A vibratory source is created in the neoesophagus, above the elephant shunt. During speech production, narrowing of the inside and vibration of the jejunal mucosa can be observed using a laryngeal fiber scope. In order to study the acoustical characteristics of shunt speech, voice analysis was performed in patients with restored phonatory function using Computerized Speech Lab Model 4300 (KAY). Irregularities of pitch periods in the voice sample were measured using Jita (the pitch period) and Jitt (relative evaluation of the pitch) for the very short term (cycle-to-cycle), and PPQ (pitch period pertubation quotient) for the short term (cycle-to-cycle with a smoothing factor of 5 periods). Irregularities of the peak-to-peak amplitude were measured using ShdB (evaluation in dB of the peak-to-peak amplitude) and Shim (relative evaluation of the peak-to-peak amplitude) for the very short term (cycle-to-cycle), and APQ (amplitude perturbation quotient) for the short term (cycle-to-cycle with a smoothing factor of 11 periods). The pertubation parameters of shunt speech are larger than normal ones not only in terms of the period but also in terms of the amplitude. These results are similar to those of laryngeal polyps, recurrent nerve palsy and esophageal speech. Recovery of phonation using Nozaki's type 3 method with the elephant nose shunt appears promising for pharyngo-laryngo-esophagectomized patients.

Ultrasonic assessment of vascular complications in coronary angiography and angioplasty after transradial approach.

The transradial approach has currently been accepted as an alternative entry method for coronary angiography and angioplasty. Vascular complications of this method were evaluated by 2-dimensional echo and color Doppler ultrasonic studies in 162 patients before, early (2+/-2 [mean+/-SD] days), and late (95+/-29 days) after catheterization. Mean age was 64+/-10 years, and 103 were men. Coronary angioplasty was performed in 59 patients (79 lesions) with angiographic success in 92%. Early after the procedure, segmental stenosis was noted in 35 patients (22%) and no flow in 15 patients (9%). Late after the procedure, segmental stenosis was noted in 2, diffuse stenosis in 36 (22%), and no flow in 8 (5%) patients. The cessation of radial artery pulse was unpalpable in only 2% of cases, whereas radial flow by color Doppler was undetectable in 9% early after the procedure. Late after the procedure, recanalization was observed in 60% of these occluded cases. Thirty-three of 86 patients (38%) with no flow or diffuse stenosis had radial artery diameters smaller than the sheath diameter, and 11 of 76 patients (14%) had radial artery diameters larger than the sheath diameter (p <0.01). Multivariate analysis revealed risk factors for vascular complications: (1) Radial artery diameter before the procedure was one of the significant and independent determinants of no flow both early (p = 0.06) and late (p = 0.004) after the procedure. (2) The difference in radial artery diameter and sheath size was related to the occurrence of diffuse stenosis late after the procedure (p = 0.003). (3) Diabetes mellitus was related to no flow (p = 0.05) or diffuse stenosis (p = 0.11) late after the procedure. Thus, ultrasonic evaluation of the radial artery was useful in selecting both an access route and an appropriate size of the sheath to determine early and late vascular complications.

Measurement of guinea pig basilar membrane using computer-aided three-dimensional reconstruction system.

Cochleas are known to have the ability to analyze a frequency widely, and this ability seems to be owed mostly to the basilar membrane (BM) configuration. However, the relationship between the cochlear frequency-position map and the BM configuration is not clear. Therefore, in this paper, the internal structures of a guinea pig cochlea, especially the BM configuration, were reconstructed and measured using a computer-aided three-dimensional (3-D) reconstruction system. Then, an attempt was made to examine the influence of the BM configuration on the cochlear frequency-position map. The measurement results indicate that the width of the BM increased and its thickness decreased with an increase in the distance from the basal turn towards the apical turn. Theoretical consideration reveals that the wide frequency-position of the cochlea is achieved by not only the BM configuration change along the length of the cochlea but also the change of the Young's modulus of the BM along the length of the cochlea.

Effect of anesthetic agents and middle ear pressure application on distortion product otoacoustic emissions in the gerbil.

The functional status of the middle ear system has a crucial importance in the measurements of distortion product otoacoustic emissions (DPOAEs), because each emission signal has to be detected indirectly in the external canal. It was observed that DPOAEs were scarcely detectable in the gerbil anesthetized with pentobarbital. On the other hand, when ketamine was used as an anesthetic, the DPOAE levels were generally high. The differences in the effects of these anesthetic agents on the DPOAEs became less clear when the tympanic bulla was opened. This strongly suggests that the effects might be due to a modification of the middle ear pressure. This study was designed to elucidate the mechanisms of the effects of these anesthetics on the DPOAEs. Comparing the effects of pentobarbital and those of pressure application to the middle ear on the frequency characteristics of DPOAEs, the following conclusions emerged: (1) pentobarbital administration causes negative middle ear pressure in the gerbil; (2) the generated pressure strongly reduces DPOAE conduction through the middle ear; and thus (3) proper selection of anesthetic agents is very important in gerbil experiments that involve OAE measurements.

[A study on monoclonal antibodies against epithelial cell of endolymphatic sac in guinea pigs].

Using a microdissected endolymphatic sac of the guinea pig (n = 35) as an initial antigen preparation, serials of monoclonal antibodies were established which were used to label the epithelial cells of endolymphatic sac. The antibodies showed strong immunoreactivity with kidney, but not with other organs. It also showed isotopes IgG1, IgG2b and IgM. The results of Western blotting and SDS-PAGE indicated that the epitopes of monoclonal antibodies were proteins or glyoprotein with a molecular weight of approximately 7,400. The locations of the epitopes in epithelial cells suggest that it may play some roles in construction and function of the endolymphatic sac.

ATP-induced increase in intracellular Ca2+ concentration in the cultured marginal cell of the stria vascularis of guinea-pigs.

The primary culture of marginal cells from the explant of the stria vascularis of guinea-pigs was established and confirmed by morphological, immunohistochemical and physiological characters of the cultivated cells. The positive stain of cytokeratin 18 without vimentin and desmin expressions indicated the epithelial origin of the cultured polygonal cells. Electron microscopical findings of cultured cells resembled the morphological characteristics of marginal cells. The addition of 100 microM ouabain to the cultured cells significantly increased the intracellular Na+ concentration, providing the evidence for the presence of Na+ pump. Using the cultured marginal cells identified by the above-mentioned findings, the effects of neurotransmitters and hormones in regulating intracellular Ca2+ concentration ([Ca2+]i) were investigated. The addition of 10(-4) M ATP caused an increase in [Ca2+]i, which was independent of the presence of extracellular Ca2+. The rank order of agonist potency was ATP > alpha, beta-methylene ATP > ADP. Adenosine, however, evoked no response. Cultured marginal cells may possess P2-purinergic receptors which mobilize Ca2+ from the intracellular Ca2+ pool.

Dysgenesis of melanocytes and cochlear dysfunction in mutant microphthalmia (mi) mice.

In order to evaluate the cytological homology of intermediate cells and melanocytes, and to investigate the function of melanocytes in the inner ear, hearing acuity and cochlear pathology were studied in three strains of mice, namely, wild type mice (+/+), albino mice without melanin (c2J/c2J), and microphthalmia mice with no melanocytes (mibw/mibw). Our histochemical data indicated that intermediate cells showed cytological characteristics almost identical to those of melanocytes and that disorders of melanin and/or melanocytes were reflected in the stria vascularis of each mouse. While c2J/c2J presented the same normal hearing acuity and normal structure of the stria vascularis as +/+, the hearing acuity of mibw/mibw mutants was severely impaired. Their stria vascularis was abnormally thin, lacking intermediate cells. According to these results, lack of melanin has little influence on hearing acuity; however, the absence of intermediate cells or melanocytes causes severe hearing loss, presumably due to a strial dysfunction.

A characteristics protein highly expressed in guinea pig inner ear, defined by monoclonal antibody WH-1.

A new monoclonal antibody (termed WH-1; isotype IgG2b) was established using a homogenate of dissected guinea pig cochleas (N = 60) as immunogen. Western blotting and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) identified the WH-1 antigen as a protein or glycoprotein with M(r) approximately 40 kDa. Immunoperoxidase treatment of histologic cryosections of guinea pig cochlea, followed by light microscopic examination, revealed strong positive staining at three sites: (i) parts of Hensen's stripe, marginal band, covering net, and Kimura's membrane (within the tectorial membrane [TM]); (ii) Deiters' cells, pillar cells, Hensen's cells, and stereocilia of outer hair cells (within the organ of Corti); (iii) interdental cells, inner and outer sulcus cells, Reissner's membrane, and surface membrane of stria vascularis epithelium. Similar staining patterns were observed for cryosections of rat and mouse cochleas. Only a trace quantity of cross-reacting protein was detectable in brainstem. The protein was not detectable in tongue extract by Western blotting. However, sections of brainstem and tongue did show positive immunohistological staining with WH-1. Localization of WH-1 antigen was further examined by electron microscopy. WH-1 positivity on outer hair cell stereocilia, certain sites on the TM, interdental cell surface, Reissner's membrane epithelia, and inner and outer sulcus cells was confirmed. WH-1 antigen was not detected on inner hair cell stereocilia by light or electron microscopy. The localization of WH-1 antigen on outer hair cell stereocilia and TM suggests that it may play some role in adhesion between these structures.

Fine structure of the lamina basilaris of guinea pig cochlea.

The lamina basilaris of guinea pig cochlea was studied with SEM after trypsin treatment, and with TEM of resin sections and deep-etching replicas. The lamina consists of radial, evenly compacted filaments in the zona arcuata, and radial, discretely bundled filaments in the zona pectinata. In both zones, elementary filaments measured about 12 nm in thickness on the replica. The filaments formed more or less irregular passing bridges with each other and, eventually, a three-dimensional network which was continuous with the basement membrane under the supporting cells.

Hearing and glycoconjugates: localization of Le(y), Le(x) and sialosyl-Le(x) in guinea pig cochlea, particularly at the tectorial membrane and sensory epithelia of the organ of Corti.

Immunohistological examination of guinea pig cochleas was performed using a panel of 25 monoclonal antibodies directed to various lacto-, ganglio- and globo-series carbohydrate epitopes as well as mucin-type epitopes. Lacto-series structures were found to be localized at specific sites of the tectorial membrane (TM) and Corti's organ, i.e. alpha 1-->3 fucosyl type 2 chain (Le(x)) at Kimura's membrane, marginal band and covering net of TM; alpha 1-->2, alpha 1-->3 difucosyl type 2 chain (Le(y)) at covering net; and sialosyl-Le(x) and sialosyl-i at Kimura's membrane and sensory epithelia, particularly sensory tips of hair cells of Corti's organ. In striking contrast, ganglio-series structures (GM3, GD3, GD2, 9-O-Ac-GD3) were detected at spiral ganglion cells, neuronal fibres and stria vascularis, but were completely absent from Corti's organ and most of the TM. Other epitope structures defined by various antibodies were not detectable at any location. The functional roles of lacto-series carbohydrate epitopes expressed at TM and Corti's organ remain unknown. However, the expression of Le(y) (but not other structures) in association with developmental deficiency of TM induced by 6-N-propyl-2-thiouracil in rats suggests that Le(y) plays some role in normal TM development. The presence of Le(x) at Kimura's membrane and sialosyl-Le(x) at hair cell sensory tips of Corti's organ suggests the intriguing possibility that these fucosylated/sialosylated carbohydrate structures play some role in interactions (either attractive or repulsive) of these inner ear components, which have been implicated in the physiology of hearing, i.e. the conversion of sound waves to nerve impulses.

Catecholaminergic innervation in the vestibular labyrinth and vestibular nucleus of guinea pigs.

The vestibular sympathetic fibers of 20 guinea pigs were examined by immunohistochemical demonstration using tyrosine hydroxylase and dopamine B-hydroxylase. The vestibular sympathetics originated in the ipsilateral superior cervical ganglion and entered the internal auditory meatus along the labyrinthine artery. At the Schwann-glial border, some of the sympathetic fibers left the artery and went into the superior and inferior divisions of the vestibular nerve and made a loose meshwork among the Scarpa's ganglion cells, while other fibers kept following the labyrinthine artery. Both groups of fibers entered the cristae ampullaris and saccular and utricular maculas after several bifurcations in the cribrose areas and terminated either near the capillaries beneath the sensory epithelia, or among the vestibular nerve fibers. These fibers travelled freely in the vestibular labyrinth without being restricted to following blood vessels or vestibular nerve fibers. Some sympathetic fibers made direct contacts with the vestibular efferent fibers or the vestibular afferent fibers at the node of Ranvier. Sympathetic fibers were not observed in the sensory epithelia or semicircular canals, and were rarely found in the vicinity of the dark cells. The vestibular nucleus was also innervated by other catecholaminergic nerve fibers originating from the locus ceruleus, and the synaptic contacts were observed between the catecholaminergic nerve terminals and other neurons. These two peripheral and central catecholaminergic nervous systems were quite independent at the level of Schwann-glial border.

Sympathetic and CGRP-positive nerve supply to the endolymphatic sac of guinea pig.

The distribution of sympathetic fibers and calcitonin gene related peptide (CGRP)-positive fibers was examined in the endolymphatic sac of 10 guinea pigs by using immunohistochemical techniques to demonstrate tyrosine hydroxylase (TH) and CGRP. A meshwork of TH-positive fibers, found around the sigmoid sinus, sent branches to the distal and the intermediate parts of the endolymphatic sac. In these areas. TH-positive fibers traveled freely from blood vessels and formed a loose plexus beneath the lining epithelium. Such fibers were rare in proximal portion of the endolymphatic sac and in the endolymphatic duct. Seven days after elimination of the ipsilateral superior cervical ganglion, some of the TH-positive fibers were gone, however, there were still a few fibers in the endolymphatic sac as well as around the sigmoid sinus, thus their origin remains obscure. CGRP-positive fibers also branched from the fibers around the sigmoid sinus, and were distributed throughout the endolymphatic sac, some occasionally extending to the endolymphatic duct. They not only formed a dense plexus in the sublining space, but also spread through the lining cell layer. Elimination of the ipsilateral superior cervical ganglion did not affect the distribution of CGRP-positive fibers, indicating that they are probably not sympathetic fibers.

MRL/MP-lpr/lpr mouse as a model of immune-induced sensorineural hearing loss.

Hearing acuity and inner ear disorders of MRL/lpr mice, bred for the study of autoimmune disease, were examined in comparison to those of BALB/c mice. The auditory brain stem response threshold of 20-week-old MRL/lpr mice was significantly higher than that of BALB/c mice of the same age (p < .01). The pathologic changes of 20-week-old MRL/lpr mice were characterized by the degeneration of intermediate cells, widened intercellular spaces, and immunoglobulin G deposition on the basement membrane of strial blood vessels as well as in the basal infolding of strial marginal cells, which were absent in BALB/c mice. That there were no other evident pathologic findings in the cochlea or middle ear suggests that these changes in the stria vascularis seemed to be responsible for the sensorineural hearing loss of this mouse. The MRL/lpr mouse was thought to be a good experimental model to study the spontaneous sensorineural hearing loss caused by an immune reaction.

Quantitative carbohydrate analyses of the tectorial and otoconial membranes of the guinea pig.

Carbohydrate composition of the tectorial membrane (TM) and the otoconial membrane (OM) of the guinea pig was analyzed after hydrolysis, using high-performance anion-exchange chromatography and pulsed amperometric detection. Both of the tissues were highly glycosylated; the carbohydrate content being 24-42% of protein. GlcN, Gal, Glc and Man were found to be the major component sugars of TM, whereas little GalN was found. Fuc and NANA were also present, but NGNA was not detectable. After digestion with thermolysin for solubilization, OM was separated into two fractions: insoluble mineral particles of the otoconia (OM-ppt) and a soluble fraction from the gelatinous layer (OM-sup). These two fractions showed distinct carbohydrate composition from each other. Further analyses using glycosidases revealed that TM contained asialyl and monosialyl but little di-, tri- and tetrasialyl N-glycosides, and OM-sup did not seem to be susceptible to endo-beta-galactosidase, which is known to cleave some N-acetyl-polylactosamine and keratan sulfate. Based on these analyses, it can be suggested that most of the carbohydrates in TM are likely to be asialyl and monosialyl N-glycosides. N-Glycosides may be predominant in the otoconia as well, and a polymer structure consisting of GlcN(Ac) and Gal other than N-acetyl-polylactosamine may exist in the gelatinous layer of OM. O-Glycosylation of the usual type appeared to be minor in all the fractions.

Effect on cochlear potentials of lateral semicircular canal destruction.

Recording of the cochlear potentials was successfully performed during experimental labyrinthectomy in the guinea pig and in three patients with acoustic neuromas during translabyrinthine removal of the tumors. In the guinea pig, complete interruption of the duct of the lateral semicircular canal including the endolymphatic canal caused little change in the endocochlear DC potential of the first cochlear turn and input-output function curve of the N1 component of the compound action potential elicited by 8-kHz tone bursts. Further drilling of the vestibular labyrinth in the guinea pig caused decline of these potentials when the vestibular was opened. In patients with acoustic neuromas, the interruption of the duct of the lateral semicircular canal hardly altered the N1 input-output function curve and N1 input-latency function curve during the 1-hour observation period. Consistent preservation of cochlear function even after interruption of lateral semicircular canals suggests the possibility of partial surgical labryrinthectomy with preservation of hearing for lesions involving semicircular canals.

Microtubule subunits of guinea pig vestibular epithelial cells.

Guinea pig cochlear supporting cells have microtubules which are composed of 15, instead of the ordinary 13, protofilaments. The microtubules form a large and stiff bundle involving abundant actin filaments to provide effective rigidity to the cell specialized for transduction of extremely high-frequent mechanical stimuli. We examined microtubules in guinea pig vestibular end organs with the transmission electron microscopy after treatment with tannic acid. Solitary microtubules occurred abundantly in the supranuclear region of type I hair cells, but sparsely in type II hair cells. Individual microtubules consisted of an ordinary set of 13 protofilaments in these hair cells as well as in the supporting cells. Supporting cells were characterized by cytoskeletal bundles of 2 to 30 microtubules which were found to be connected with actin filaments via cross-linking units. Results from the present investigation indicate that such less-organized microtubules of 13 protofilaments are sufficient for vestibular supporting cells which are specialized for detection of lower-frequency vibration together with fellow sensory cells.