China
Africa
Explore chapters and articles related to this topic
Anatomy of the Cochlea and Vestibular System: Relating Ultrastructure to Function
Published in John C Watkinson, Raymond W Clarke, Christopher P Aldren, Doris-Eva Bamiou, Raymond W Clarke, Richard M Irving, Haytham Kubba, Shakeel R Saeed, Paediatrics, The Ear, Skull Base, 2018
The tectorial membrane (TM) is the structured sheet of extracellular matrix material that overlies the organ of Corti (Figures 47.1b and 47.4b,g). At its inner edge it is attached to the interdental cells of the spiral limbus, a bony prominence to the inside of the organ of Corti (Figure 47.1b). It appears not to be attached to the surface of the organ of Corti at its outer edge. The longest stereocilia of each OHC are embedded in the underside of the TM (further described below). The TM is not merely a fibrous mass but it is quite highly structured, with a defined shape (Figure 47.1b). Its thickness decreases and its radial length increases systematically from base to apex. Over the top surface densely packed fibres are arranged in a network, the ‘covernet’ (Figure 47.4g), that is not unlike the perforated sheet of the otoconial membrane. The outermost tip is also distinguished by a higher density of fibre packing (Figure 47.4b,g). On the underside – facing the apical surface of the organ of Corti – there is a thickened ridge known as Hensen’s stripe located just lateral to the position of the IHC stereocilia which is thought to contribute to the fluid-coupled deflection of the IHC stereocilia.
Effects of basilar-membrane lesions on dynamic responses of the middle ear
Published in Acta Oto-Laryngologica, 2023
Junyi Liang, Wen Xie, Wenjuan Yao, Maoli Duan
Some disorders of metabolism in the cochlear such as mucopolysaccharidosis can cause basilar membrane damage or an increase the sensory cell weight. In addition, the mass of the spiral limbus cells, spiral process, and the spiral ligament increases notably [16]. All these structures are within the organ of Corti, which attaches to the basilar membrane. As a result, added mass of the basilar membrane increases. In addition, some genetic defects can lead to congenital deafness. The main characteristics embody in the hypertrophy of Sertoli cells in cortis device, leads to the increase of the basilar membrane mass. Added mass in the basilar membrane was adopted as the following situation: average thickness increased 0.15 mm, while the added mass is 36 × 10−9 kg. Under 90 dB SPL, compared with the normal human ear, the frequency-response curve of displacement and velocity were respectively obtained, as shown in Figure 7.
Prevention of progressive hearing loss in a mouse model of diabetes by oral intake of eicosapentaenoic acid ethyl ester
Published in Acta Oto-Laryngologica, 2023
Takafumi Matsuura, Kazuma Sugahara, Yohei Yamamoto, Junko Tsuda, Makoto Hashimoto, Hiroshi Yamashita
Immunostaining results suggested that EPA administration promotes BDNF expression in the inner ear. There was no difference in the organ of corti, but BDNF expression was conspicuous in the TSOD (EPA+) group in the spiral limbus and spiral ganglion cells. In a study on guinea pig cochlea, polysialic acid was detected in the spiral limbus [18]. Polysialic acid has been reported to function as a reservoir for several neurotrophic factors including BDNF [19]. In addition to the prevention of spiral ganglion cell reduction and degeneration, the expression of BDNF in the spiral ganglion cells was more noticeable in the TSOD (EPA+) group than in the TSNO group. BDNF regulates SGN survival and neurite outgrowth in the developing cochlea [20]. Exogenous BDNF administered to the ears of hearing-impaired patients significantly enhances SGN survival and neurite remodeling [10]. It has been suggested that BDNF expression induced by EPA administration contributes to the prevention of spiral ganglion cell degeneration and decreases.
Human cochlear microanatomy – an electron microscopy and super-resolution structured illumination study and review
Published in Hearing, Balance and Communication, 2020
Wei Liu, Rudolf Glueckert, Annelies Schrott-Fischer, Helge Rask-Andersen
The undersurface displays radial fibre bundles running from the marginal band to Hensen’s stripe with direct connections. An intriguing observation is that vibrations are conveyed directly from OHCs to IHCs via functional radial fibres that couple the two hair cell systems. Similarly, radial coupling might synchronize equally tuned OHCs to enhance sensitivity and frequency resolution [50]. However, SEM showed no cilia imprints on Hensen’s stripe, similar to earlier reports [31,51] suggesting that IHC bundles are freestanding, although physical contact could occur during BM motion [29]. In another human SEM study, imprints of IHC bundles were found in the basal turn but not in the apical and middle turns [30]. Another option for the IHCs to be activated is through the sub-tectorial fluid. At some frequencies the TM and RL oscillations influence the sub-tectorial fluid space that, in itself, could couple OHCs and IHCs [52]. We also localized the inner ear-specific protein otoancorin expressed on the spiral limbus and believed to be indispensable for TM attachment to the spiral limbus [44,53]. The gene OTOA encoding the protein was found to be mutated in non-syndromic recessive deafness DFNB22.