Human Ossicles Research Articles

Study of Morphological and Anthropometric Features of Human Ear Ossicles.

To study the morphology and anthropometry of human ear ossicles from cadaveric temporal bone and to study the variations of the human ossicles from ossiculoplasty point of view. 38 sets of ear ossicles were collected, each containing malleus, incus and stapes, from temporal bone dissection done in Vasantrao Pawar medical college, Nashik. They were studied under microscope & anthropometrical, morphological evaluation done. Malleus showed variations in handle where 61% were straight and 39% curved. Weight of malleus ranged from 0.03-0.06gm. The length ranged from 5.5 to 8.2mm. Incus showed morphological variation in lenticular process which was present in 73% incii. Weight of incus ranged from 0.04 to 0.09gm, average length of long process 3.5mm, width of body 4mm. In stapes variations was seen with head of stapes which was absent in 21% bones. With increasing awareness about postop hearing status, this study will add up in knowledge of morphological and anthropometric variations that exists in Indian population, help otologists to understand middle ear dynamics better which will improve results of ossiculoplasty.

Anatomical and morphometric study of goat middle ear ossicles (Capra aegagrus hircus)

ABSTRACT The social and economic roles of goat farming in Northeastern Brazil, allied to the fact that the use of goat middle ear ossicles for research and human ear surgery training has not yet been proposed, justify the study of their applicability as an experimental model. The middle ears of 19 goats (Capra aegagrus hircus) from the bone collection of the Laboratory and Didactic Anatomy Museum of Domestic and Wild Animals of the Federal University of Vale do São Francisco (UNIVASF) were dissected. The malleus, incus, and stapes were evaluated regarding their macroscopic morphology and biometry (length, width, and height). Ossicle morphology was similar to sheep, human, and bovine morphology. The malleus was 1.3 times heavier and 2.2 times longer than the incus, and 9.0 times heavier and 3.7 times longer than the stapes. The size relationship was positive between the stapes and the malleus and negative between the stapes and the incus. It is concluded that the middle ear size and the anatomical similarities with human ossicles make goats a useful model for experimental scientific studies, reconstructive surgery practice of the ossicular chain, and human ear surgery training.

Micro-CT of the human ossicular chain: Statistical shape modeling and implications for otologic surgery.

The ossicular chain is a middle ear structure consisting of the small incus, malleus and stapes bones, which transmit tympanic membrane vibrations caused by sound to the inner ear. Despite being shown to be highly variable in shape, there are very few morphological studies of the ossicles. The objective of this study was to use a large sample of cadaveric ossicles to create a set of three-dimensional models and study their statistical variance. Thirty-three cadaveric temporal bone samples were scanned using micro-computed tomography (μCT) and segmented. Statistical shape models (SSMs) were then made for each ossicle to demonstrate the divergence of morphological features. Results revealed that ossicles were most likely to vary in overall size, but that more specific feature variability was found at the manubrium of the malleus, the long process and lenticular process of the incus, and the crura and footplate of the stapes. By analyzing samples as whole ossicular chains, it was revealed that when fixed at the malleus, changes along the chain resulted in a wide variety of final stapes positions. This is the first known study to create high-quality, three-dimensional SSMs of the human ossicles. This information can be used to guide otological surgical training and planning, inform ossicular prosthesis development, and assist with other ossicular studies and applications by improving automated segmentation algorithms. All models have been made publicly available.

Precision Medicine in Ossiculoplasty.

Long term results of ossiculoplasty surgery are considered poor with displacement and extrusion amongst the common reasons for failure. Application of 3Dimensional (3D) printing may help overcome some of these barriers, however digital methods to attain accurate 3D morphological studies of ossicular anatomy are lacking, exacerbated by the limitation of resolution of clinical imaging. 20 human cadaveric temporal bones were assessed using micro computed tomography (CT) imaging to demonstrate the lowest resolution required for accurate 3D reconstruction. The bones were then scanned using conebeam CT (125 μm) and helical CT (0.6 mm). 3D reconstruction using clinical imaging techniques with microCT imaging (40 μm resolution) as a reference was assessed. The incus was chosen as the focus of study. Two different methods of 3D printing techniques were assessed. A minimum resolution of 100 μm was needed for adequate 3D reconstruction of the ossicular chain. Conebeam CT gave the most accurate data on 3D analysis, producing the smallest mean variation in surface topography data relative to microCT (mean difference 0.037 mm, p < 0.001). Though the incus varied in shape in between people, paired matches were identical. Thus, the contralateral side can be used for 3D printing source data if the ipsilateral incus is missing. Laser based 3D printing was superior to extrusion based printing to achieve the resolution demands for 3D printed ossicles. Resolution of modern imaging allows 3D reconstructions and 3D printing of human ossicles with good accuracy, though it is important to pay attention to thresholding during this process.

Study on the mechanism of sound conduction of the reconstructive model of human auditory ossicles

Study on the mechanism of sound conduction of the reconstructive model of human auditory ossicles

Comparison of sheep and human middle-ear ossicles: anatomy and inertial properties

The sheep middle ear has been used in training to prepare physicians to perform surgeries and to test new ways of surgical access. This study aimed to (1) collect anatomical data and inertial properties of the sheep middle-ear ossicles and (2) explore effects of these features on sound transmission, in comparison to those of the human. Characteristic dimensions and inertial properties of the middle-ear ossicles of White-Alpine sheep (n = 11) were measured from high-resolution micro-CT data, and were assessed in comparison with the corresponding values of the human middle ear. The sheep middle-ear ossicles differed from those of human in several ways: anteroinferior orientation of the malleus handle, relatively small size of the incus with a relatively short distance to the lenticular process, a large area of the articular surfaces at the incudostapedial joint, and a relatively small moment of inertia along the anterior–posterior axis. Analysis in this study suggests that structure and orientation of the middle-ear ossicles in the sheep are conducive to an increase in the hinge-like ossicular-lever-action around the anterior–posterior axis. Considering the substantial anatomical differences, outcomes of middle-ear surgeries would presumably be difficult to assess from experiments using the sheep middle ear.

Bone mineral density of human ear ossicles: An assessment of structure in relation to function.

Human ear ossicles are essential for normal sound conduction from the external environment to the inner ear. These bones are subjected to high biomechanical loads due to the sustained vibrations which occur with reception of sound. It is expected that the bones would undergo a significant amount of remodeling and change in bone mineral density during the lifespan of an individual. Therefore, the aim of the study was to evaluate the possible changes in bone mineral density of regions of the ossicular chain during postnatal life. Forty four left and 36 right sets of human ear ossicles, ranging from a sub-adult age group to a mature adult age group, were sourced from the School of Anatomical Sciences, University of Witwatersrand. The ear ossicles were scanned using a micro-focus CT X-ray. A three-dimensional reconstruction of each ossicle was created from the CT scan. Bone mineral density was then determined at specific sites on the ossicles. There was no statistically significant variation found in the bone mineral density in relation to the age of the specimens. However, the handle of the malleus, the incudo-stapedial joint and the insertion site for the tendon of stapedius had lower bone mineral densities when compared to adjacent articulation and nonattachment sites on the ossicular chain. This is possibly due to biomechanical stress in response to sound conduction rather than ageing. Lower bone mineral density may be indicative of regions that experience the highest biomechanical force, thus, resulting in increased remodeling. Clin. Anat. 31:1158-1166, 2018. © 2018 Wiley Periodicals, Inc.

Engineered humanized bone organs maintain human hematopoiesis in vivo

Hematopoietic stem cells (HSCs) are maintained in a specialized bone marrow (BM) environment, the so-called HSC niche, that provides pivotal factors for their maintenance. Although the cellular and molecular components of the mouse BM HSC niche have been extensively studied using genetically modified animals, relatively little is known about the counterpart human BM niche components. We previously illustrated, with a developmental tissue engineering approach, that human adult BM-derived mesenchymal stromal cells (MSCs) can develop into human bone organs (so-called ossicles) through endochondral ossification in vivo and that these human ossicles are able to maintain functional mouse HSCs. We here report that human ossicles in immunodeficient mice maintain human immature and mature hematopoiesis in vivo. Moreover, a higher percentage of human stem and progenitor cells are kept in quiescence in human ossicles as compared with mouse BM. These findings indicate that the human MSC-derived ossicles function as a hematopoietic niche and may potentially serve as a re-engineerable platform to study normal and diseased human hematopoiesis in a physiologically optimized environment.

A novel auditory ossicles membrane and the development of conductive hearing loss in Dmp1-null mice

Genetic mouse models are widely used for understanding human diseases but we know much less about the anatomical structure of the auditory ossicles in the mouse than we do about human ossicles. Furthermore, current studies have mainly focused on disease conditions such as osteomalacia and rickets in patients with hypophosphatemia rickets, although the reason that these patients develop late-onset hearing loss is unknown. In this study, we first analyzed Dmp1 lac Z knock-in auditory ossicles (in which the blue reporter is used to trace DMP1 expression in osteocytes) using X-gal staining and discovered a novel bony membrane surrounding the mouse malleus. This finding was further confirmed by 3-D micro-CT, X-ray, and alizarin red stained images. We speculate that this unique structure amplifies and facilitates sound wave transmissions in two ways: increasing the contact surface between the eardrum and malleus and accelerating the sound transmission due to its mineral content. Next, we documented a progressive deterioration in the Dmp1-null auditory ossicle structures using multiple imaging techniques. The auditory brainstem response test demonstrated a conductive hearing loss in the adult Dmp1-null mice. This finding may help to explain in part why patients with DMP1 mutations develop late-onset hearing loss, and supports the critical role of DMP1 in maintaining the integrity of the auditory ossicles and its bony membrane.

Development and analysis of three-dimensional (3D) printed biomimetic ceramic

Many finite element (FE) models have been designed based on geometric information from computed tomography (CT) data, and validated via comparison with experimental results for human cadaver ossicular bones. Here, we describe a novel method for developing and analyzing the biomimetic ceramic ossicles (BCO) in combination with 3D printing technology, and we establish an FE model of the BCO for analyzing vibration performance. Novel biomimetic ceramic ossicles (BCO) made of hydroxyapatite (HA) were fabricated using 3D printing technology, and their vibration properties were measured. We created a 3D model of the BCO using computer-aided design, which corresponds to the ossicular structure and geometry, and created an FE model of the human ossicles via a comparison of experimental and simulated vibrations to investigate the characteristics of the ossicular chain. The FE model was established based on the displacements of the malleus, incus, and stapes, which was analyzed using an externally applied vibrational force.

ヒト耳小骨の振動解析

ヒト耳小骨の振動解析

Bone quality and biomechanical function: A lesson from human ossicles

In humans, the middle ear contains a chain of three ossicles with a major highly specific mechanical property (transmission of vibrations) and modeling that stops rapidly after birth. Their bone quality has been rarely studied either in noninflammatory ossicles or in those from ears with chronic inflammation. Our primary goal was to assess bone microarchitecture, morphology and variables reflecting bone quality from incuses, in comparison with those from human femoral cortical bone as controls. Secondly, the impact of chronic inflammation on quality of ossicles was documented. The study was performed on 15 noninflammatory incuses from 15 patients (35±32years, range: 2–91). Comparisons were performed with 13 inflammatory incuses from 13 patients (55±20years, range: 1–79) with chronic inflammation of the middle ear, essentially cholesteatoma. Microarchitecture and bone mineral density (BMD) were assessed by microcomputed tomography. Microhardness was measured by microindentation. Mineral and organic characteristics were investigated by Fourier transform infrared microspectroscopy. Noninflammatory incuses were composed of a compact, well mineralized bone without bone marrow and with sparse vessels. Remodeling activity was rarely observed. Woven or lamellar textures and numerous osteocytes were observed. In inflammatory incuses, architecture was degraded, organic tissue was abundant and bone cavities contained fibrocellular tissue and adipocytes. BMD of noninflammatory incuses was significantly higher than BMD from both control bones (4 embedded cortical femoral bone samples; age: 72±15years, range: 50–85) and inflammatory incuses. Noninflammatory incuses were less hard than both control bone (8 cortical femoral bone samples; age: 49±18years, range: 24–74) and inflammatory incuses. All incuses were more mineralized and less mature than controls. In conclusion, bone quality of incuses (dense, well mineralized, hard) is well adapted to their function of sound transmission. In inflammatory condition, incuses were degraded, thus explaining the decline of hearing. Moreover, microhardness was found higher than in noninflammatory incuses. Compared to bone with remodeling, the mineralization index in incuses does not explain variation of microhardness. Interestingly, a linear multiple regression model indicated that a combination of two variables, i.e., crystallinity index (crystal size/perfection) and carbonation (incorporation of carbonate ions in apatite) explains 26% of the increase in microhardness variability. Because the low remodeling level of ossicles could not prevent the reversibility of their degradation which impacts audition quality, an early management of ear inflammation in chronic otitis is recommended.

A Novel Humanized Bone Marrow Niche Xenotransplantation Model Allows Superior Engraftment of Human Normal and Malignant Hematopoietic Cells and Reveals Myelofibrosis-Initiating Cells in the HSC Compartment

Xenotransplantation into immunocompromised mice is a powerful tool for studying human normal and malignant hematopoiesis. However, xenotransplant models do not necessarily recapitulate human physiology since environmental factors provided by bone marrow (BM) niche cells may differ between mice and humans. Although existing mouse models allow for propagation of hematopoietic stem and progenitor cells (HSPCs) and aggressive acute leukemias, engraftment of more committed normal progenitor cells and many other hematopoietic malignancies is still lacking. Here, we report the development of a novel mouse model bearing a subcutaneously accessible human bone ossicle formed by in situ differentiation of BM-derived mesenchymal stromal cells (MSCs). These human ossicles contain a functional humanized BM niche that facilitates robust engraftment of normal human HSPC and exhibits superior engraftment and expansion of primary AML. Interestingly, this model allows robust engraftment of PML-RARA positive APL and JAK2 V617F+ PMF, both of which fail to engraft in conventional xenotransplantation models.Subcutaneous injection of human BM-derived MSCs resulted in the formation of human ossicles through endochondral ossification resulting in a bone marrow cavity harboring normal mouse hematopoietic elements. After conditioning irradiation, direct intraossicle injection of cord blood CD34+ HSPC (n=5) resulted in robust multi-lineage human engraftment including B cells, T cells, NK cells, mature neutrophils, eosinophils, monocytes, as well as red blood cell precursors and platelets, as assessed by flow cytometric analysis of aspirates taken directly from the ossicles. The self-renewal potential of engrafted HSPCs was demonstrated by re-establishing multi-lineage hematopoiesis in secondary recipients. Unlike conventional NSG mice, this xenograft model allowed engraftment of phenotypically defined L-MPP (n=7) and GMP (n=7). Engraftment analysis 2 weeks post transplantation showed human engraftment with a majority of CD33+ myeloid cells (LMPP: 77.3±14.4%; GMP: 97.3±1.8%) and intermediate (LMPP: 20.8±14.4%) to low (GMP: 1.8±1.8%) numbers of B lymphoid cells.In the investigation of AML, direct intraossicle transplantation of blasts (n=5) resulted in faster (as early as 6 weeks) and significantly higher leukemic engraftment in humanized niches compared to mouse BM. Furthermore, engraftment was also significantly higher in humanized niches after intravenous transplantation and demonstrated a paratrabecular engraftment pattern, suggesting preferential homing and expansion of AML cells in a human BM microenvironment. Limiting dilution analysis revealed a 10-250 fold higher leukemia-initiating cell frequency using direct intraossicle transplantation compared to intrafemoral injection into mouse BM. Intraossicle transplantation also allowed for engraftment and propagation of PML-RARA-positive APL blasts (n=3) resulting in almost 100% leukemic chimerism and granulocytic sarcoma formation 10-15 weeks post-transplantation. Finally, transplantation of PMF patient-derived CD34+ cells (n=5) into the humanized niche led to robust engraftment with up to 50% human chimerism, and further subpopulation studies demonstrated that PMF-engraftment was exclusively initiated from the HSC (CD34+/CD38-/CD90+) population. Engrafted cells showed marked myeloid skewing with JAK2 V617F-positive cells, and detection of only minimal JAK2 wild type lymphoid cells.In summary, we report the development of a novel xenotransplantation model using human bone ossicles formed by in situ differentiation of BM-derived MSCs that substantially improves the engraftment of normal and malignant hematopoietic populations, leading to the formal demonstration that PMF-initiating cells reside in the immunophenotypic HSC compartment. DisclosuresNo relevant conflicts of interest to declare.

The Non-Invasive Measurement of Geometry of Human Ossicles

This study is to reconstruct the 3D model of ossicles by the smoothing technique that fitted to the human ossicles. The length of the geometry of the model was then measured. The image of human ossicles was obtained by the micro computed tomography scan. The 3D model of human ossicles was reconstructed by image processing, and then the length of the geometry of the 3D model was measured. The 3D model of human ossicles was reconstructed by image processing and by surface smoothing technique in this study. The surface of the ossicles model was smoothed by Smoothsurface. The length of the short process of the incus was 1.8 mm. The length of the long process of the incus was 5.2 mm. Based on the results obtained by this study, there was almost no difference for the measurements of the lengths of the cadaver malleus and incus between by observation and by image processing. Therefore, the image processing method was convenient and reliable. By the 3D model of ossicles, the clinician could know the structure of middle ear and could diagnose the middle ear disease more exactly.

Optimal ossicular site for maximal vibration transmissions to coupled transducers

Totally implantable middle-ear prosthetic devices, such as the Esteem system (Envoy Medical Corporation), detect vibrational motion of the middle-ear ossicles rather than acoustic stimulation to the eardrum. This eliminates the need for a subcutaneous microphone, which is susceptible to interference by ambient noises. Study of the vibrational characteristics of the human ossicles provides valuable information for determining the site of maximum ossicular motion that would be optimal for attachment of the sensor portion of the prosthesis. In this study, vibrational responses at seven locations on the middle-ear ossicles (i.e., the malleus head, 4 different points on the incus body, middle of the incus long process, tip of the incus long process) in human temporal bones (n = 6) were measured using a laser Doppler vibrometer. The measurements were repeated after separating the incudostapedial joint (ISJ). Measured displacement at each location was normalized with the sound pressure level near the tympanic membrane (TM) for representation in the form of a displacement transfer function (DTF). The normalized squared sum of the DTFs (NSSDTF) was then calculated as a measure of vibration motion through a specific frequency range at the considered sites. The relatively large NSSDTF was observed at the sites on the superior part of the malleus head (MH), on the lateral part of the incus body (IBL), and on the superior part of the incus body near the incudomalleal joint (IBS1) for the frequency ranges of 1–4 kHz and 1–9 kHz, regardless of the condition of the ISJ. This indicates that maximum vibrational motion of the middle-ear is deliverable to the piezoelectric transducer of totally implantable devices through these sites.This article is part of a Special Issue entitled “MEMRO 2012”.

Effects of High Hydrostatic Pressure on Bacterial Growth on Human Ossicles Explanted from Cholesteatoma Patients

BackgroundHigh hydrostatic pressure (HHP) treatment can eliminate cholesteatoma cells from explanted human ossicles prior to re-insertion. We analyzed the effects of HHP treatment on the microbial flora on ossicles and on the planktonic and biofilm states of selected isolates.MethodologyTwenty-six ossicles were explanted from cholesteatoma patients. Five ossicles were directly analyzed for microbial growth without further treatment. Fifteen ossicles were cut into two pieces. One piece was exposed to HHP of 350 MPa for 10 minutes. Both the treated and untreated (control) pieces were then assessed semi-quantitatively. Three ossicles were cut into two pieces and exposed to identical pressure conditions with or without the addition of one of two different combinations of antibiotics to the medium.Differential effects of 10-minute in vitro exposure of planktonic and biofilm bacteria to pressures of 100 MPa, 250 MPa, 400 MPa and 540 MPa in isotonic and hypotonic media were analyzed using two patient isolates of Staphylococcus epidermidis and Neisseria subflava. Bacterial cell inactivation and biofilm destruction were assessed by colony counting and electron microscopy.Principal FindingsA variety of microorganisms were isolated from the ossicles. Irrespective of the medium, HHP treatment at 350 MPa for 10 minutes led to satisfying but incomplete inactivation especially of Gram-negative bacteria. The addition of antibiotics increased the efficacy of elimination. A comparison of HHP treatment of planktonic and biofilm cells showed that the effects of HPP were reduced by about one decadic logarithmic unit when HPP was applied to biofilms.High hydrostatic pressure conditions that are suitable to inactivate cholesteatoma cells fail to completely sterilize ossicles even if antibiotics are added. As a result of the reduced microbial load and the viability loss of surviving bacteria, however, there is a lower risk of re-infection after re-insertion.

Role of osteocyte apoptosis in peculiar ossicles of the hearing sense organ: preliminary observations on hearing loss and osteoporosis

Starting point of the present study is the osteocyte role in bone remodelling that allows bone adaptation to mechanical load [1-3]. Bone remodelling has been investigated in relation to the occurrence of apoptosis [4] to understand if and how the process of programmed cell death interferes with bone turnover. In 1998, in a study on human middle ear, Marotti et al. [5] demonstrated that: 1) over 40% of osteocytes are dead within the 2nd year of age (but the authors were not able to demonstrate if osteocyte death occurred by degeneration or apoptosis); 2) bone remodelling occurs only occasionally. Recently [6], we showed that: 1) osteocytes of human auditory ossicles die by apoptosis; 2) also osteocytes located inside scleral ossicles of lower vertebrate eye (reptiles and birds) phylogenetically so far from human auditory ossicles are widely affected by apoptosis (about 60%); 3) in scleral ossicles bone turnover never occur. It is to be noted that both auditory ossicles of human ear and scleral ossicles of vertebrate eye are peculiar bony segments continuously submitted to stereotyped stresses and strains, with specialized functions: the first are involved in sound wave transmission and the latter protect the eyeball against deformation during the movement and have a role in visual accomodation, providing attachment for the ciliary muscles. In both cases, bone remodelling might severely impair, by resorption, the mechanical resistance of these extremely small specialized bony segments. Thus, we suggested that in auditory and scleral ossicles, submitted to stereotyped loading for all life, bone mechanical adaptation is not needed and osteocyte programmed death could represent the mechanism to avoid bone remodelling and to make stable, when necessary, bone structure and mechanical resistance. More recently, to confirm this hypothesis, clinical data were collected from a cohort of patients aged 55-85 years affected by hearing loss. The main target of the present study is to exclude any correlation between hearing loss and osteoporosis. During osteoporosis, unbalanced bone turnover causes the bone depletion in skeletal segments; such condition, in the peculiar ossicles of human middle ear, should imply hearing impairment. Our preliminary observations indicate, instead, that osteoporotic patients do not show higher percentage of hearing loss with respect to non osteoporotic ones. This evidence is ascribable to osteocyte apoptosis of auditory ossicles that avoid bone remodelling, thus assuring the integrity of such bony segments also in osteoporotic conditions.

Smoothing for the Optimal Surface of a 3D Image Model of the Human Ossicles

ABSTRACTThis study assessed the optimal process for the surface smoothing of 3D image models of in vivo human ossicles. A 3D image model of the ossicles was reconstructed from high resolution computed tomography imaging data. Three smoothing methods including constrained smoothing, unconstrained smoothing and smoothsurface will be discussed. The volume of the 3D image model produced by unconstrained smoothing differed substantially from the original model volume prior to smoothing. Constrained smoothing had an uneven effect on the surface of the 3D image models. Using the smoothsurface module, we were able to obtain an optimal surface of the 3D image model of the human ossicles including the malleus, incus and stapes, using 20 iterations and a λ value of 0.6.

Retraction: Volume Fraction of the Human Pathologic Ossicles Destructed by Cholesteatoma Using Micro-CT

Background and Objectives：Conventional studies for the middle ear ossicles destructed by cholesteatoma give relatively limited information on shape, mechanical strength and 3-dimensional relationship. Recently, Micro-CT scanning technology has been applied to analysis of skeletal structure. This study aims to reconstruct the 3-dimensional structure of normal ossicles and destructed ossicles by different cholesteatomas and to compare volume fraction of destructed ossicles with that of normal ossicles. Materials and Method：13 pathological ossicles obtained during cholesteatoma surgery were used in this study (2 malleuses and 2 incuses from attic cholesteatoma；1 malleus and 2 incuses from sinus cholesteatoma;2 malleuses and 2 incuses from tensa retraction cholesteatoma；2 incuses from congenital cholesteatoma). As a control, normal ossicles harvested from cadaveric temporal bone specimens were used. The structure of obtained ossicles was analyzed through Micro-CT (SkySan-1072, Belgium) by filming the 2-dimensional cross section image running perpendicular to the long axis of the ossicles. The 3-dimensional images were thereby reconstructed for each, and were analyzed using CT-AnalyzerTM and ANTTM. Based on the results, the strength of each ossicle were measured. Results：The volume fraction, indicating relative strengths of ossicles, was lower in the portion of destructed surface. The pattern of destructed ossicles by cholesteatoma was different according to pathological status of cholesteatoma. Conclusion：Our preliminary data of ossicular structure analyzed by Micro-CT scan will be helpful for elucidation of pathological ossicles in middle ear cholesteatoma and will make a great contribution to research of middle ear cholesteatoma.

Three‐Dimensional Anatomy of the Temporal Bone in Normal Mice

This study was performed to determine the three-dimensional (3D) structure of the murine temporal bone and to provide a survey atlas of the temporal bone structures in mice. The temporal bones of adult BALB/c mice were examined and 3D high-resolution reconstructions of the temporal bone were obtained using a micro-CT system. Using the system described here, the bony labyrinth and membranous labyrinth could be investigated in a non-destructive manner. The turning rate of the cochlea was two (human rate: two and a half). The shapes of the superior and posterior semicircular canals were more flexed than those in humans. The malleus manubrium was directed anteriorly and was thin and fan-shaped like a Persian sword. The size of the incus relative to the malleus was smaller than that in the human ossicles. The 3D reconstruction of murine temporal bone described in this study provides anatomical information that will be useful in future studies using mouse model.