Gata2 is required for the development of inner ear semicircular ducts and the surrounding perilymphatic space

Objective: To compare the quality of perilymphatic enhancement in the rat inner ear after intratympanic injection of two types of gadolinium with a 9.4-tesla micro-MRI. Materials and Methods: Gadolinium was injected into the middle ear in 6 Sprague-Dawley rats via the transtympanic route. The left ear was injected with Gd-DO3A-butrol first, and then the right ear was injected with Gd-DOTA. MR images of the inner ear were acquired 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4 h after intratympanic (IT) injection using an Agilent MRI system 9.4T/160/AS. The normalized signal intensity was quantitatively analyzed at the scala vestibuli (SV), scala media, and scala tympani (ST) using a Marosis M-view system. Then the normalized signal intensities (SIs) were compared between the two contrast agents. Results: For Gd-DO3A-butrol, the SI was as low as 1.0-1.5 throughout 1-4 h at the SV and ST of the basal turn. The maximum SI was 1.5 ± 0.5 at the SV (2 h) and 1.3 ± 0.5 at the ST (2 h). For Gd-DOTA, the 1-hour postinjection SI at the basal turn was 2.5 ± 0.5 at the SV, 1.6 ± 0.3 at the ST, and 1.2 ± 0.3 at the scala media. In the apical turn, the maximum SI was reached after 2.5 h. The maximum SI in the apical turn was 1.8 ± 0.4 at the SV (3.5 h), 1.8 ± 0.4 at the ST (4 h), and 1.4 ± 0.3 at the scala media (4 h). Conclusions: We were able to clearly visualize and separate the ST and SV using IT Gd and 9.4-tesla micro-MRI. We recommend using Gd-DO3A-butrol over Gd-DOTA and to perform the MRI 2.5 h after using IT Gd in the rat inner ear.

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Lymphocytic Streaming as an Indicator of Inner Ear Compartmentalization

Otolaryngology ◽

10.1177/019459988108900527 ◽

1981 ◽

Vol 89 (5) ◽

pp. 836-840

Author(s):

George Roffman ◽

Richard W. Babin

Keyword(s):

Central Nervous System ◽

Cerebrospinal Fluid ◽

Nervous System ◽

Inner Ear ◽

Lymphoblastic Leukemia ◽

Cochlear Aqueduct ◽

Fluid Channel ◽

Temporal Bones ◽

Perilymphatic Space ◽

Physiologic Data

Despite a great deal of anatomic and physiologic data in animals, controversy still exists over whether or not the perilymphatic space in man is directly connected to the intracranial space via a patent cochlear aqueduct or other fluid channel. Human physiologic data are limited, indirect, and conflicting. Anatomic and pathologic data have heretofor been inadequate for answering the question convincingly. The temporal bones of a 19-year-old woman with central nervous system lymphoblastic leukemia are discussed. The passive-appearing movement of lymphoblasts between cerebrospinal fluid and perilymphatic spaces suggests both a functionally patent cochlear aqueduct and alternate pathways.

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Three-Dimensional Volumetric Measurement of Endolymphatic Hydrops in Meniere's Disease

Frontiers in Neurology ◽

10.3389/fneur.2021.710422 ◽

2021 ◽

Vol 12 ◽

Author(s):

Tae-Soo Noh ◽

Moo Kyun Park ◽

Jun Ho Lee ◽

Seung Ha Oh ◽

Ji-Hoon Kim ◽

...

Keyword(s):

Diagnostic Accuracy ◽

Inner Ear ◽

Phased Array ◽

Endolymphatic Hydrops ◽

Three Dimensional ◽

3D Analysis ◽

Volumetric Measurement ◽

Advantages And Disadvantages ◽

Perilymphatic Space ◽

Array Coil

Objective: We used volumetric three-dimensional (3D) analysis to quantitatively evaluate the extent of endolymphatic hydrops (EH) in the entire inner ear. We tested for correlations between the planimetric and volumetric measurements, to identify their advantages and disadvantages.Methods: HYDROPS2-Mi2 EH images were acquired for 32 ears (16 patients): 16 ipsilateral ears of MD patients (MD-ears) and 16 contralateral ears. Three-T MR unit with a 32-channel phased-array coil/the contrast agent to fill the perilymphatic space and the HYDROPS2-Mi2 sequence. We calculated the EH% [(endolymph)/(endolymph+perilymph)] ratio and analyzed the entire inner ear in terms of the volumetric EH% value, but only single cochlear and vestibular slices were subjected to planimetric EH% evaluation. The EH% values were compared between MD ears and non-MD ears, to evaluate the diagnostic accuracy of the two methods.Results: The volumetric EH% was significantly higher for MD vestibules (50.76 ± 13.78%) than non-MD vestibules (39.50 ± 8.99%). The planimetric EH% was also significantly higher for MD vestibules (61.98 ± 20.65%) than non-MD vestibules (37.22 ± 12.95%). The vestibular and cochlear volumetric EH% values correlated significantly with the planimetric EH% values of the MD ear.Conclusion: Volumetric and planimetric EH measurements facilitate diagnosis of MD ears compared to non-MD ears. Both methods seem to be reliable and consistent; the measurements were significantly correlated in this study. However, the planimetric EH% overestimates the extent of vestibular hydrops by 26.26%. Also, planimetric data may not correlate with volumetric data for non-MD cochleae with normal EH% values.

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Effect of CO2 on the Perilymphatic Oxygen Tension in Cats

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348947708600205 ◽

1977 ◽

Vol 86 (2) ◽

pp. 164-171 ◽

Cited By ~ 19

Author(s):

K. Murata ◽

U. Fisch

Keyword(s):

Blood Flow ◽

Inner Ear ◽

Oxygen Content ◽

Oxygen Tension ◽

Experimental Animal ◽

Pure Oxygen ◽

Actual Degree ◽

Adult Cats ◽

Perilymphatic Space ◽

Inner Ear Fluids

A microelectrode with a tip of 100μ permitting recording of the oxygen tension in the perilymphatic space according to the polarographic principle and having a minimal drift of 1–2.5% per hour has been developed. The effects of apnea, hypo- and hyperventilation as well as those of inhalation of pure oxygen, and CO2 upon the perilymphatic Po2 have been measured by placing the electrode in the perilymph through the fenestrated stapedial footplate of 87 adult cats. The correlation between the arterial Pco2 and the perilymphatic Po2 is so close that even hypo- or hyperventilation in presence of air does influence the oxygen content of the perilymphatic space. In view of the effect of the smallest accumulation of alveolar CO2, particular attention has to be paid to the system used for respiration of the experimental animal, when determining the action of drugs or inhaled gas mixtures on the oxygenation of the inner ear fluids. The measurement of the perilymphatic oxygen tension also indicates that the rate of blood flow cannot be used to deduct with accuracy the actual degree of oxygenation of the inner ear fluids.

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Diagnostic value of three-dimensional magnetic resonance imaging of inner ear after intratympanic gadolinium injection, and clinical application of magnetic resonance imaging scoring system in patients with delayed endolymphatic hydrops

The Journal of Laryngology & Otology ◽

10.1017/s0022215113003289 ◽

2013 ◽

Vol 128 (1) ◽

pp. 53-59 ◽

Cited By ~ 6

Author(s):

X Gu ◽

Z-M Fang ◽

Y Liu ◽

S-L Lin ◽

B Han ◽

...

Keyword(s):

Magnetic Resonance Imaging ◽

Magnetic Resonance ◽

Inner Ear ◽

Endolymphatic Hydrops ◽

Three Dimensional ◽

Resonance Imaging ◽

Positive Identification ◽

Delayed Endolymphatic Hydrops ◽

Intratympanic Injection ◽

Perilymphatic Space

AbstractObjective:Three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging of the inner ear after intratympanic injection of gadolinium, together with magnetic resonance imaging scoring of the perilymphatic space, were used to investigate the positive identification rate of hydrops and determine the technique's diagnostic value for delayed endolymphatic hydrops.Methods:Twenty-five patients with delayed endolymphatic hydrops underwent pure tone audiometry, bithermal caloric testing, vestibular-evoked myogenic potential testing and three-dimensional magnetic resonance imaging of the inner ear after bilateral intratympanic injection of gadolinium. The perilymphatic space of the scanned images was analysed to investigate the positive identification rate of endolymphatic hydrops.Results:According to the magnetic resonance imaging scoring of the perilymphatic space and the diagnostic standard, 84 per cent of the patients examined had endolymphatic hydrops. In comparison, the positive identification rates for vestibular-evoked myogenic potential and bithermal caloric testing were 52 per cent and 72 per cent respectively.Conclusion:Three-dimensional magnetic resonance imaging after intratympanic injection of gadolinium is valuable in the diagnosis of delayed endolymphatic hydrops and its classification. The perilymphatic space scoring system improved the diagnostic accuracy of magnetic resonance imaging.

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Development of Intercellular Junctions in the Vestibular End-Organ

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348948409300120 ◽

1984 ◽

Vol 93 (1) ◽

pp. 89-95 ◽

Cited By ~ 12

Author(s):

Dan Bagger-Sjöbäck ◽

Matti Anniko

Keyword(s):

Gap Junctions ◽

Inner Ear ◽

Tight Junctions ◽

Hair Cells ◽

Intercellular Junctions ◽

Supporting Cells ◽

Fluid Compartments ◽

Well Differentiated ◽

Gap Junctional ◽

Perilymphatic Space

The intercellular junctions and the tight junctions in particular are considered to be of great importance for the function of the inner ear. The two fluid compartments of the inner ear, the perilymphatic space and the endolymphatic space, need to be effectively separated from each other in order to maintain the ionic gradients between the two. The tight junctional structures have been described in mature animals of several species. In the present article the development and maturation of the intercellular junctions are described in the mouse embryo. Junctional elements are already present in the 12th gestational day otocyst. Over the next few days, the otocyst is differentiated into a cochlear portion and a vestibular portion. The tight junctions in the vestibular portion gradually attain their mature appearance. It seems as if the tight junctions of the supporting cells develop slightly faster than those of the hair cells. At the time of birth, all epithelial cells have obtained mature appearance. The tight junctions are fully developed on the supporting cells as well as the hair cells. Small gap junctions are present in the 14th gestational day specimens. Two days later the hair cells and the supporting cells are well differentiated; small to medium-sized gap junctions are present only on the supporting cells at this stage. At the time of birth larger gap junctional aggregates have developed on the supporting cells.

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Inner ear biomechanics reveals Late Triassic origin of mammalian endothermy

10.21203/rs.3.rs-570966/v1 ◽

2021 ◽

Author(s):

Ricardo Araujo ◽

Romain David ◽

Julien Benoit ◽

Lungmus Jacqueline ◽

Fred Spoor ◽

...

Keyword(s):

Inner Ear ◽

Cross Sections ◽

Motor Coordination ◽

Morphological Changes ◽

Physiological Characteristic ◽

Late Triassic ◽

New Information ◽

Ecological Dominance ◽

Semicircular Ducts ◽

Head Rotations

Abstract Endothermy (“warm-bloodedness”) underpins the ecological dominance of mammals and birds in diverse environmental settings1-3. However, it is unclear when this crucial feature emerged during mammalian evolutionary history, as most fossil evidence is ambiguous4-25. Here, we show that new information on this key evolutionary transition can be obtained from the morphology of the endolymph-filled semicircular ducts of the inner ear that monitor head rotations and are essential for motor coordination, navigation, and spatial awareness26-31. Increased body temperature during the ectotherm–endotherm transition of mammal ancestors would decrease endolymph viscosity, negatively impacting the biomechanics of the semicircular ducts32,33, while simultaneously increasing activity levels34,35 required improved performance36. Specific morphological changes to the membranous ducts and enclosing bony canals were, therefore, necessary to maintain optimal functionality. We track these morphological changes in 341 vertebrates, including 56 extinct synapsids, and show that canals with relatively thin cross-sections and small radii of curvature are indicative of mammalian endothermy. This inner ear morphotype evolved abruptly ~233 million years ago, during the Late Triassic, in Mammaliamorpha. Our conclusion differs from previous suggestions3-17, and we interpret most stem-mammals as ectotherms. Endothermy as a crucial physiological characteristic joins other distinctive mammalian features that arose during this period of climatic instability37-39.

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Hmx2 homeobox gene control of murine vestibular morphogenesis

Development ◽

10.1242/dev.128.24.5017 ◽

2001 ◽

Vol 128 (24) ◽

pp. 5017-5029 ◽

Cited By ~ 2

Author(s):

Weidong Wang ◽

Edwin K. Chan ◽

Shira Baron ◽

Thomas Van De Water ◽

Thomas Lufkin

Keyword(s):

Inner Ear ◽

Cell Fate ◽

Critical Role ◽

Homeobox Gene ◽

Significant Loss ◽

Targeted Disruption ◽

Surface Ectoderm ◽

Dorsal Portion ◽

Temporal And Spatial ◽

Semicircular Ducts

Development of the vertebrate inner ear is characterized by a series of genetically programmed events involving induction of surface ectoderm, preliminary morphogenesis, specification and commitment of sensory, nonsensory and neuronal cells, as well as outgrowth and restructuring of the otocyst to form a complex labyrinth. Hmx2, a member of the Hmx homeobox gene family, is coexpressed with Hmx3 in the dorsolateral otic epithelium. Targeted disruption of Hmx2 in mice demonstrates the temporal and spatial involvement of Hmx2 in the embryonic transition of the dorsal portion (pars superior) of the otocyst to a fully developed vestibular system. In Hmx2 null embryos, a perturbation in cell fate determination in the lateral aspect of the otic epithelium results in reduced cell proliferation in epithelial cells, which includes the vestibular sensory patches and semicircular duct fusion plates, as well as in the adjacent mesenchyme. Consequently, enlargement and morphogenesis of the pars superior of the otocyst to form a complex labyrinth of cavities and ducts is blocked, as indicated by the lack of any distinguishable semicircular ducts, persistence of the primordial vestibular diverticula, significant loss in the three cristae and the macula utriculus, and a fused utriculosaccular chamber. The developmental regulators Bmp4, Dlx5 and Pax2 all play a critical role in inner ear ontogeny, and the expression of each of these genes is affected in the Hmx2 null otocyst suggesting a complex regulatory role for Hmx2 in this genetic cascade. Both Hmx2 and Hmx3 transcripts are coexpressed in the developing central nervous system including the neural tube and hypothalamus. A lack of defects in the CNS, coupled with the fact that not all of the Hmx2-positive regions in developing inner ear are impaired in the Hmx2 null mice, suggest that Hmx2 and Hmx3 have both unique and overlapping functions during embryogenesis.

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Endotoxic damage to the stria vascularis: the pathogenesis of sensorineural hearing loss secondary to otitis media?

The Journal of Laryngology & Otology ◽

10.1017/s0022215100126623 ◽

1994 ◽

Vol 108 (4) ◽

pp. 310-313 ◽

Cited By ~ 24

Author(s):

Yangchun Guo ◽

Yiqin Wu ◽

Wenlie Chen ◽

Jizhen Lin

Keyword(s):

Inner Ear ◽

Otitis Media ◽

Stria Vascularis ◽

Animal Experiments ◽

Organ Of Corti ◽

Control Group ◽

Structural Evaluation ◽

Ion Imbalance ◽

Secondary Lysosomes ◽

Perilymphatic Space

AbstractThis study presents animal experiments on endotoxin (lipopolysaccharides: LPS) damage to the inner ear with special reference to the stria vascularis. The experimental group animals (albino guinea pigs) were injected with LPS into the perilymphatic space. Pyrogen-free saline (PFS) was injected into the control group. Strial structural evaluation and hearing tests were carried out before and one, three and five days after treatment. In PFS-treated (control) ears, no significant change was found either in hearing or structure. However, thresholds of Nl/Pl were elevated and latencies prolonged in LPS-treated ears. They had severe strial damage mainly to the cellular organelles. The mitochondria became swollen with a disordered, broken, degenerated or absent crest. Secondary lysosomes and autophagosomes increased in number with the presence of medulative inclusions. Na+-K+-ATPase reactant was obviously diminished. It is concluded that LPS-induced strial ototoxicityproduces ion imbalance, causing changesin endolymph composition and energy failure in the organ of Corti and is also responsible for the pathogenesis of inner ear sequelae secondary to otitis media.

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