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Journal of Anatomy Apr 2014The young of marsupials and monotremes are all born in an immature state, followed by prolonged nurturing by maternal lactation in either a pouch or nest. Nevertheless,...
The young of marsupials and monotremes are all born in an immature state, followed by prolonged nurturing by maternal lactation in either a pouch or nest. Nevertheless, the level of locomotor ability required for newborn marsupials and monotremes to reach the safety of the pouch or nest varies considerably: some are transferred to the pouch or nest in an egg (monotremes); others are transferred passively by gravity (e.g. dasyurid marsupials); some have only a horizontal wriggle to make (e.g. peramelid and didelphid marsupials); and others must climb vertically for a long distance to reach the maternal pouch (e.g. diprotodontid marsupials). In the present study, archived sections of the inner ear and hindbrain held in the Bolk, Hill and Hubrecht collections at the Museum für Naturkunde, Berlin, were used to test the relationship between structural maturity of the vestibular apparatus and the locomotor challenges that face the young of these different mammalian groups. A system for staging different levels of structural maturity of the vestibular apparatus was applied to the embryos, pouch young and hatchlings, and correlated with somatic size as indicated by greatest body length. Dasyurids are born at the most immature state, with the vestibular apparatus at little more than the otocyst stage. Peramelids are born with the vestibular apparatus at a more mature state (fully developed semicircular ducts and a ductus reuniens forming between the cochlear duct and saccule, but no semicircular canals). Diprotodontids and monotremes are born with the vestibular apparatus at the most mature state for the non-eutherians (semicircular canals formed, maculae present, but vestibular nuclei in the brainstem not yet differentiated). Monotremes and marsupials reach the later stages of vestibular apparatus development at mean body lengths that lie within the range of those found for laboratory rodents (mouse and rat) reaching the same vestibular stage.
Topics: Animals; Marsupialia; Monotremata; Species Specificity; Vestibule, Labyrinth
PubMed: 24298911
DOI: 10.1111/joa.12148 -
Journal of Toxicologic Pathology Jul 2022Vestibular organs consist of the maculae staticae, which are located in both the utricle and saccule, as well as the semicircular ducts and their ampullas. There have...
Vestibular organs consist of the maculae staticae, which are located in both the utricle and saccule, as well as the semicircular ducts and their ampullas. There have been no reports on specimen preparation methods for vestibular organs, including maculae staticae or semicircular ducts. In this study, we investigated highly reproducible methods of preparing vestibular organ specimens for histopathological examinations. We established a method that allows researchers to observe the utricle and saccule, including otoliths, the ampulla of a semicircular duct, and parts of semicircular ducts. This highly reproducible method is useful for histopathological analysis of mice with symptoms of abnormal equilibrium caused by medical toxicity and genetic modification.
PubMed: 35832898
DOI: 10.1293/tox.2022-0008 -
Scientific Reports Jul 2023Considerable diversity has been documented in most sensory systems of elasmobranchs (sharks, rays, and skates); however, relatively little is known about morphological...
Considerable diversity has been documented in most sensory systems of elasmobranchs (sharks, rays, and skates); however, relatively little is known about morphological variation in the auditory system of these fishes. Using magnetic resonance imaging (MRI), the inner ear structures of 26 elasmobranchs were assessed in situ. The inner ear end organs (saccule, lagena, utricle, and macula neglecta), semi-circular canals (horizontal, anterior, and posterior), and endolymphatic duct were compared using phylogenetically-informed, multivariate analyses. Inner ear variation can be characterised by three primary axes that are influenced by diet and habitat, where piscivorous elasmobranchs have larger inner ears compared to non-piscivorous species, and reef-associated species have larger inner ears than oceanic species. Importantly, this variation may reflect differences in auditory specialisation that could be tied to the functional requirements and environmental soundscapes of different species.
Topics: Animals; Endolymphatic Duct; Semicircular Canals; Sharks; Skates, Fish; Kidney Tubules
PubMed: 37488259
DOI: 10.1038/s41598-023-39151-0 -
Frontiers in Surgery 2021The etiology of Meniere's disease (MD) and endolymphatic hydrops believed to underlie its symptoms remain unknown. One reason may be the exceptional complexity of the...
The etiology of Meniere's disease (MD) and endolymphatic hydrops believed to underlie its symptoms remain unknown. One reason may be the exceptional complexity of the human inner ear, its vulnerability, and surrounding hard bone. The vestibular organ contains an endolymphatic duct system (EDS) bridging the different fluid reservoirs. It may be essential for monitoring hydraulic equilibrium, and a dysregulation may result in distension of the fluid spaces or endolymphatic hydrops. We studied the EDS using high-resolution synchrotron phase contrast non-invasive imaging (SR-PCI), and micro-computed tomography (micro-CT). Ten fresh human temporal bones underwent SR-PCI. One bone underwent micro-CT after fixation and staining with Lugol's iodine solution (IKI) to increase tissue resolution. Data were processed using volume-rendering software to create 3D reconstructions allowing orthogonal sectioning, cropping, and tissue segmentation. Combined imaging techniques with segmentation and tissue modeling demonstrated the 3D anatomy of the human saccule, utricle, endolymphatic duct, and sac together with connecting pathways. The utricular duct (UD) and utriculo-endolymphatic valve (UEV or Bast's valve) were demonstrated three-dimensionally for the first time. The reunion duct was displayed with micro-CT. It may serve as a safety valve to maintain cochlear endolymph homeostasis under certain conditions. The thin reunion duct seems to play a minor role in the exchange of endolymph between the cochlea and vestibule under normal conditions. The saccule wall appears highly flexible, which may explain occult hydrops occasionally preceding symptoms in MD on magnetic resonance imaging (MRI). The design of the UEV and connecting ducts suggests that there is a reciprocal exchange of fluid among the utricle, semicircular canals, and the EDS. Based on the anatomic framework and previous experimental data, we speculate that precipitous vestibular symptoms in MD arise from a sudden increase in endolymph pressure caused by an uncontrolled endolymphatic sac secretion. A rapid rise in UD pressure, mediated along the fairly wide UEV, may underlie the acute vertigo attack, refuting the rupture/K-intoxication theory.
PubMed: 34136526
DOI: 10.3389/fsurg.2021.662530 -
Biophysical Journal Sep 2017The semicircular canals are biomechanical sensors responsible for detecting and encoding angular motion of the head in 3D space. Canal afferent neurons provide essential...
The semicircular canals are biomechanical sensors responsible for detecting and encoding angular motion of the head in 3D space. Canal afferent neurons provide essential inputs to neural circuits responsible for representation of self-position/orientation in space, and to compensatory circuits including the vestibulo-ocular and vestibulo-collic reflex arcs. In this work we derive, to our knowledge, a new 1D mathematical model quantifying canal biomechanics based on the morphology, dynamics of the inner ear fluids, and membranous labyrinth deformability. The model takes the form of a dispersive wave equation and predicts canal responses to angular motion, sound, and mechanical stimulation. Numerical simulations were carried out for the morphology of the human lateral canal using known physical properties of the endolymph and perilymph in three diverse conditions: surgical plugging, rotation, and mechanical indentation. The model reproduces frequency-dependent attenuation and phase shift in cases of canal plugging. During rotation, duct deformability extends the frequency bandwidth and enhances the high frequency gain. Mechanical indentation of the membranous duct at high frequencies evokes traveling waves that move away from the location of indentation and at low frequencies compels endolymph displacement along the canal. These results demonstrate the importance of the conformal perilymph-filled bony labyrinth to pressure changes and to high frequency sound and vibration.
Topics: Animals; Batrachoidiformes; Biomechanical Phenomena; Computer Simulation; Head Movements; Humans; Hydrodynamics; Linear Models; Models, Biological; Motion; Physical Stimulation; Pressure; Rotation; Semicircular Canals; Sound; Vibration; Viscosity
PubMed: 28877495
DOI: 10.1016/j.bpj.2017.08.001 -
Journal of Otology Jun 2015Preparation of the temporal bone for light microscopy is an important step in histological studies of the inner ear. Due to the complexity of structures of the inner...
Preparation of the temporal bone for light microscopy is an important step in histological studies of the inner ear. Due to the complexity of structures of the inner ear, it is difficult to measure or compare structures of interest without a commonly accepted standardized measure of temporal bone sections. Therefore, standardization of temporal bone sections is very important for histological assessment of sensory hair cells and peripheral ganglion neurons in the cochlear and vestibular systems. The standardized temporal bone sectioning is oriented to a plane parallel to the outer and internal auditory canals. Sections are collected from the epitympanum to the hypotympanum to reveal layers in the order of the crista ampullaris of the superior and lateral semicircular canals, macula utriculi and macula sacculi, superior vestibular ganglion neurons, macula of saccule and inferior vestibular ganglion neurons, cochlear modiolus, endolymphatic duct and endolymphatic sac, and finally the crista ampullaris of the posterior semicircular canal. Moreover, technical details of preparing for temporal bone sectioning including fixation, decalcification, whole temporal bone staining, embedding penetration, and embedding orientation are also discussed.
PubMed: 29937784
DOI: 10.1016/j.joto.2015.08.001 -
Journal of Anatomy Jul 2017The labyrinth has two functional parts: the cochlea for audition and the vestibular system for equilibrioception. In the latter, the semicircular ducts and the otolithic... (Comparative Study)
Comparative Study
The labyrinth has two functional parts: the cochlea for audition and the vestibular system for equilibrioception. In the latter, the semicircular ducts and the otolithic organs are sensitive to rotational and linear accelerations of the head, respectively. The labyrinthine morphology influences perception accuracy, hence the adaptation to a specific locomotor pattern. The aim of this study is to determine the relationship between locomotion and semicircular canal morphology using geometric morphometrics, and to explain these links with existing functional models. The influence of factors other than functional constraints on labyrinthine morphology is discussed. The left bony labyrinth of 65 specimens was extracted virtually. Five extant hominoid species with various locomotion modes were sampled. A set of 13 landmarks was placed on the semicircular canals. After a Procrustes fit, their coordinates were analyzed using a principal component analysis. It was found that labyrinthine morphology is significantly distinct between species. More specifically, the differences involve a posterolateral projection of the lateral semicircular canal and the rotation of this canal relative to the vertical canals. This rotation occurs in the sagittal plane, which is consistent with previous studies based on traditional morphometrics. Among extant hominoids, the shape of the canals potentially discriminates species based on posture. This result could be used to reconstruct the locomotor pattern of fossil hominoids.
Topics: Animals; Biometry; Female; Hominidae; Humans; Locomotion; Male; Phylogeny; Principal Component Analysis; Semicircular Canals
PubMed: 28523740
DOI: 10.1111/joa.12619 -
World Journal of Otorhinolaryngology -... Jan 2021To develop a downloadable three-dimensional (3D) study tool of the membranous labyrinth in order to facilitate the study of benign paroxysmal positional vertigo (BPPV).
OBJECTIVE
To develop a downloadable three-dimensional (3D) study tool of the membranous labyrinth in order to facilitate the study of benign paroxysmal positional vertigo (BPPV).
BACKGROUND
The diagnosis and treatment of BPPV depend on an understanding of the anatomy of the vestibular labyrinth and its position relative to the head. To date, many illustrations have been made to explain principles of diagnosis and treatment of BPPV, but few have been based on anatomical studies of the membranous labyrinth.
METHODS
A previously reported 3D model of a human labyrinth was transposed to a 3D development software to allow the creation of markers along the semicircular ducts and utricle. These markers represent otoliths at different positions during movement of the model within the 3D environment. User-friendly tools were created to navigate the model, to allow clear documentation and communication of studied problems, and to study the model across relevant planes. The final model can be downloaded and is available for general useat https://bppvviewer.com/download/.
RESULTS
The model allows visualization of true membranous labyrinth anatomy in both ears simultaneously. The dependent portion of each semicircular duct, the planes of the cristae, and the position of the utricle can easily be visualized in any head position. Moveable markers can mark the expected progress of otolith debris with changes in head position and images can be captured to document simulations in various draw styles.
CONCLUSION
This simple model could offer insights that lead to more accurate diagnosis and treatment of BPPV. It may also be useful as a tool to teach BPPV.
PubMed: 33474542
DOI: 10.1016/j.wjorl.2018.10.001 -
The Journal of Neuroscience : the... Jun 2018LIM-domain containing transcription factors (LIM-TFs) are conserved factors important for embryogenesis. The specificity of these factors in transcriptional regulation...
LIM-domain containing transcription factors (LIM-TFs) are conserved factors important for embryogenesis. The specificity of these factors in transcriptional regulation is conferred by the complexes that they form with other proteins such as LIM-domain-binding (Ldb) proteins and LIM-domain only (LMO) proteins. Unlike LIM-TFs, these proteins do not bind DNA directly. LMO proteins are negative regulators of LIM-TFs and function by competing with LIM-TFs for binding to Ldb's. Although the LIM-TF Lmx1a is expressed in the developing mouse hindbrain, which provides many of the extrinsic signals for inner ear formation, conditional knock-out embryos of both sexes show that the inner ear source of Lmx1a is the major contributor of ear patterning. In addition, we have found that the reciprocal interaction between Lmx1a and Lmo4 (a LMO protein within the inner ear) mediates the formation of both vestibular and auditory structures. Lmo4 negatively regulates Lmx1a to form the three sensory cristae, the anterior semicircular canal, and the shape of the utricle in the vestibule. Furthermore, this negative regulation blocks ectopic sensory formation in the cochlea. In contrast, Lmx1a negatively regulates Lmo4 in mediating epithelial resorption of the canal pouch, which gives rise to the anterior and posterior semicircular canals. We also found that Lmx1a is independently required for the formation of the endolymphatic duct and hair cells in the basal cochlear region. The mammalian inner ear is a structurally complex organ responsible for detecting sound and maintaining balance. Failure to form the intricate 3D structure of this organ properly during development most likely will result in sensory deficits on some level. Here, we provide genetic evidence that a transcription factor, Lmx1a, interacts with its negative regulator, Lmo4, to pattern various vestibular and auditory components of the mammalian inner ear. Identifying these key molecules that mediate formation of this important sensory organ will be helpful for designing strategies and therapeutics to alleviate hearing loss and balance disorders.
Topics: Adaptor Proteins, Signal Transducing; Animals; Ear, Inner; LIM Domain Proteins; LIM-Homeodomain Proteins; Mice; Mice, Knockout; Transcription Factors
PubMed: 29769265
DOI: 10.1523/JNEUROSCI.2484-17.2018 -
Scientific Reports Mar 2019The galls induced by Schlechtendaia chinensis, Schlechtendaia peitan and Nurudea shiraii on Rhus chinensis and gall induced by Kaburagia rhusicola rhusicola on Rhus...
The galls induced by Schlechtendaia chinensis, Schlechtendaia peitan and Nurudea shiraii on Rhus chinensis and gall induced by Kaburagia rhusicola rhusicola on Rhus potaninii Maxim. are the largest plant galls and have great economic and medical values. We examined the structures of galls and their functional adaptation using various macro- and microscopic techniques. The highly adapted structures include a stalk at the base that is specialized for mechanical support and transport of nutrients for aphids, and a network of vascular bundles which accompanying schizogenous ducts arranged in a way to best support aphid feeding and population growth. There are many circular and semicircular xylems traces in an ensiform gall in cross sectional views, which would provide more nutrition and occupy less space. We infer the evolution trail was flower-like gall, horned gall, circular gall and ensiform gall. And the possible evolutionary trend of the gall was bigger chamber, more stable mechanical supporting, easier for exchanging substance and transporting nutrients.
Topics: Adaptation, Physiological; Animals; Aphids; Biological Evolution; Host-Parasite Interactions; Image Processing, Computer-Assisted; Plant Tumors; Rhus
PubMed: 30914739
DOI: 10.1038/s41598-019-41656-6