Morphological Study of the Cells in the Planum Semilunatum

Harada, Yasuo; Tagashira, Nobuharu; Hirakawa, Katsuhiro

doi:10.3109/00016488909139015

Cited by 5 publications

(6 citation statements)

References 3 publications

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“…Following fusion, these plates are resorbed through apoptosis. In the above example, this process forms the anterior and posterior canals, with the common crux situated between them although there appears to be some variation in the composition and function of endolymph-producing cells surrounding the various sensory epithelia between species (Dohlman, 1965;Harada et al, 1989;Hommerich, 1990;Kimura et al, 1964;Villegas et al, 2001;Wangemann, 1995). However, one gene that has been found to be essential for the development and function of both dark and marginal cells is the estrogen-related receptor beta, Nr3b2 (Chen & Nathans, 2007;Wangemann, 1995).…”

Section: Produc Tion and Maintenan Ce Of Endolymphmentioning

confidence: 99%

Development and evolution of the vestibular apparatuses of the inner ear

et al. 2021

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The vertebrate inner ear is a labyrinthine sensory organ responsible for perceiving sound and body motion. While a great deal of research has been invested in understanding the auditory system, a growing body of work has begun to delineate the complex developmental program behind the apparatuses of the inner ear involved with vestibular function. These animal studies have helped identify genes involved in inner ear development and model syndromes known to include vestibular dysfunction, paving the way for generating treatments for people suffering from these disorders. This review will provide an overview of known inner ear anatomy and function and summarize the exciting discoveries behind inner ear development and the evolution of its vestibular apparatuses.

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Section: Produc Tion and Maintenan Ce Of Endolymphmentioning

confidence: 99%

Development and evolution of the vestibular apparatuses of the inner ear

et al. 2021

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“…The cupula has a markedly smooth surface where it touches the ampulla wall (3,4). The ampulla wall in this region consists of special, very at, hexagonal cells (5). In their studies, Hillman and McLaren (2) showed that the adherence of the cupula to the ampulla wall is crucial to the functioning of the semicircular canal ampulla.…”

Section: Introductionmentioning

confidence: 99%

Altered Cupular Mechanics: A Cause of Peripheral Vestibular Disorders?

Helling

Watanabe

Jijiwa

et al. 2002

Acta Oto-Laryngologica

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It has taken many decades to arrive at today's concept of cupula mechanics in the stimulation of endolymphatic flows on the hair cells in the ampullae of the semicircular canal. While Steinhausen assumed free swing-door movement of the cupula in the 1930s, Hillman was the first to demonstrate firm cupula attachment to the ampulla wall as a physiological necessity in the 1970s. In contrast to the present clinical concepts of acute peripheral vestibular functional disorders (circulatory disturbances, viral or bacterial infection, altered electrolytes in the endolymph), this study examines the extent to which an impaired attachment mechanism can trigger peripheral vestibular disorders. For this purpose, we used a pigeon model (n = 8), in which mechanical detachment of the cupula from the ampulla wall was achieved by means of a targeted pressure increase in the ampulla of the lateral semicircular canal. In two additional animals the labyrinth was completely destroyed on one side in order to directly compare partial and complete vestibular disorders. In this way partial damage to the lateral semicircular canal ampulla presents a clinical picture whose symptoms are very similar to those of an idiopathic vestibular disorder in humans. Their intensity and course of compensation differ markedly from the symptoms of complete vestibular destruction. Subsequent histological examination revealed that the hair cells remained intact during the experimental detachment of the cupula. Our results thus show that only altered cupula mechanics seem to trigger the clinical picture of a peripheral vestibular disorder. This may result in completely new approaches to differential diagnosis and the therapy of vestibular neuronitis.

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“…They are further characterized by a pale cytoplasm that inspired their name, and prominent gap junction connections [Becerra and Anadon, 1993;Kikuchi et al, 1994;Villegas et al, 2001;Helling and Merker, 2005]. Membrane projections or interdigitations with neighboring cells are also commonly observed [Dohlman, 1964;Kimura et al, 1964;Harada et al, 1989;ten Cate and Rarey, 1992]. Light cells may show low NKA activity [Kawasaki et al, 1992].…”

Section: Cell Types and Mechanisms Of Endolymph Production And Ep Genmentioning

confidence: 99%

“…However, the socalled typical ionocytes of the teleost vestibular system are clearly the equivalent, and possibly the homologs, of dark cells. Ionocytes share salient properties with dark cells, such as a high density of mitochondria and vacuoles suggestive of a secretory function [Becerra and Anadon, 1993], apical microvilli [Dohlman, 1964;Harada et al, 1989;Hommerich, 1990;Becerra and Anadon, 1993] and an absence of gap junctions [Becerra and Anadon, 1993;Kikuchi et al, 1994;Villegas et al, 2001]. Ionocytes differ from dark cells primarily by having a smooth basal surface.…”

Section: Cell Types and Mechanisms Of Endolymph Production And Ep Genmentioning

confidence: 99%

“…We suggest that they are distinguished by an absence of apical microvilli [Dohlman, 1964;Harada et al, 1989;Hommerich, 1990;ten Cate and Rarey, 1992;Becerra and Anadon, 1993]. They are further characterized by a pale cytoplasm that inspired their name, and prominent gap junction connections [Becerra and Anadon, 1993;Kikuchi et al, 1994;Villegas et al, 2001;Helling and Merker, 2005].…”

Section: Cell Types and Mechanisms Of Endolymph Production And Ep Genmentioning

confidence: 99%

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Evolution of Endolymph Secretion and Endolymphatic Potential Generation in the Vertebrate Inner Ear

et al. 2018

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The ear of extant vertebrates reflects multiple independent evolutionary trajectories. Examples include the middle ear or the unique specializations of the mammalian cochlea. Another striking difference between vertebrate inner ears concerns the differences in the magnitude of the endolymphatic potential. This differs both between the vestibular and auditory part of the inner ear as well as between the auditory periphery in different vertebrates. Here we provide a comparison of the cellular and molecular mechanisms in different endorgans across vertebrates. We begin with the lateral line and vestibular systems, as they likely represent plesiomorphic conditions, then review the situation in different vertebrate auditory endorgans. All three systems harbor hair cells bathed in a high (K⁺) environment. Superficial lateral line neuromasts are bathed in an electrogenically maintained high (K⁺) microenvironment provided by the complex gelatinous cupula. This is associated with a positive endocupular potential. Whether this is a special or a universal feature of lateral line and possibly vestibular cupulae remains to be discovered. The vestibular system represents a closed system with an endolymph that is characterized by an enhanced (K⁺) relative to the perilymph. Yet only in land vertebrates does (K⁺) exceed (Na⁺). The endolymphatic potential ranges from +1 to +11 mV, albeit we note intriguing reports of substantially higher potentials of up to +70 mV in the cupula of ampullae of the semicircular canals. Similarly, in the auditory system, a high (K⁺) is observed. However, in contrast to the vestibular system, the positive endolymphatic potential varies more substantially between vertebrates, ranging from near zero mV to approximately +100 mV. The tissues generating endolymph in the inner ear show considerable differences in cell types and location. So-called dark cells and the possibly homologous ionocytes in fish appear to be the common elements, but there is always at least one additional cell type present. To inspire research in this field, we propose a classification for these cell types and discuss potential evolutionary relationships. Their molecular repertoire is largely unknown and provides further fertile ground for future investigation. Finally, we propose that the ultimate selective pressure for an increased endolymphatic potential, as observed in mammals and to a lesser extent in birds, is specifically to maintain the AC component of the hair-cell receptor potential at high frequencies. In summary, we identify intriguing questions for future directions of research into the molecular and cellular basis of the endolymph in the different compartments of the inner ear. The answers will provide important insights into evolutionary and developmental processes in a sensory organ essential to many species, including humans.

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Morphological Study of the Cells in the Planum Semilunatum

Cited by 5 publications

References 3 publications

Development and evolution of the vestibular apparatuses of the inner ear

Development and evolution of the vestibular apparatuses of the inner ear

Altered Cupular Mechanics: A Cause of Peripheral Vestibular Disorders?

Evolution of Endolymph Secretion and Endolymphatic Potential Generation in the Vertebrate Inner Ear

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