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Cho KH, Kim JH, Honkura Y, Yamamoto M, Murakami G, Rodríguez-Vázquez JF, Katori Y. Cochlear aqueduct revisited: A histological study using human fetuses. Ann Anat 2024; 253:152236. [PMID: 38417484 DOI: 10.1016/j.aanat.2024.152236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 12/04/2023] [Accepted: 02/20/2024] [Indexed: 03/01/2024]
Abstract
BACKGROUND AND AIM The cochlear aqueduct (CA) connects between the perilymphatic space of the cochlea and the subarachnoid space in the posterior cranial fossa. The study aimed to examine 1) whether cavitation of the CA occurs on the subarachnoid side or the cochlear side and 2) the growth and/or degeneration of the CA and its concomitant vein. METHODS We examined paraffin-embedded histological sections from human fetuses: 15 midterm fetuses (crown-rump length or CRL, 39-115 mm) and 12 near-term fetuses (CRL, 225-328 mm). RESULTS A linear mesenchymal condensation, i.e., a likely candidate of the CA anlage, was observed without the accompanying vein at 9-10 weeks. The vein appeared until 15 weeks, but it was sometimes distant from the CA. At 10-12 weeks, the subarachnoid space (or the epidural space) near the glossopharyngeal nerve rapidly protruded into the CA anlage and reached the scala tympani, in which cavitation was gradually on-going but without epithelial lining. However, CA cavitation did not to occur in the anlage. At the opening to the scala, the epithelial-like lining of the CA lost its meningeal structure. At near-term, the CA was often narrowed and obliterated. CONCLUSION The CA develops from meningeal tissues when the cavitation of the scala begins. The latter cavitation seemed to reduce tissue stiffness leading, to meningeal protrusion. The so-called anlage of CA might be a phylogenetic remnant of the glossopharyngeal nerve branch. A course of cochlear veins appears to be determined by a rule different from the CA development.
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Affiliation(s)
- Kwang Ho Cho
- Department of Neurology, Wonkwang University School of Medicine and Hospital, Institute of Wonkwang Medical Science, Iksan, Republic of Korea.
| | - Ji Hyun Kim
- Department of Anatomy, Jeonbuk National University Medical School, Jeonju, Republic of Korea.
| | - Yohei Honkura
- Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | - Masahito Yamamoto
- Department of Anatomy, Division of Basic Medical Science, Tokai University School of Medicine, Japan.
| | - Gen Murakami
- Division of Internal Medicine, Cupid Clinic, Iwamizawa, Japan.
| | | | - Yukio Katori
- Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
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Rodríguez-Vázquez JF, Iglesias-Moreno MC, Poch A, Murakami G, Abe H, Honkura Y. Fetal development and growth of the fissula ante fenestram in the human ear. Anat Rec (Hoboken) 2021; 305:424-435. [PMID: 34240820 DOI: 10.1002/ar.24711] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 05/08/2021] [Accepted: 06/01/2021] [Indexed: 11/07/2022]
Abstract
Since the fissula ante fenestram (FAF) is considered as a focus of otosclerotic lesion and a route of perilymph leakage, there are few description of prenatal development of the cartilaginous canal passing though the cochlear wall. We examined the sagittal and frontal histological sections of the ear from 32 human fetuses at 8-37 weeks of gestational age. At 8-12 weeks, in the immediately anterior side of a connection between the cochlear and canalicular parts of the otic capsule cartilage, the FAF appeared as a tear of a cartilage between the basal and second turns of the cochlea. The tear became a slit opening to the scala vestibuli. At 13-15 weeks, the FAF, less than 1.2 mm in length, had the anterosuperior and postero-inferior apertures: the former was near the geniculate ganglion and became closed after 15 weeks, while the latter approached the oval window. Third trimester fetuses, the FAF, 1.5-2.0 mm in length, consistently carried a single, postero-inferior aperture extending along the anterior margin of the oval window and it contained no definite epithelium and vessel. Although it was endochondral ossification, there was no clear zonation in cartilage cells of the FAF. A mechanical stress during three-dimensional coiling of the cochlear ducts seemed to provide the FAF. After the FAF was established, the stapes footplate might use a part of the inferior aperture for the syndesmosis. A specific ossification was seen in the FAF, but it might rarely cause the pathological syndesmosis.
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Affiliation(s)
| | | | - Adriana Poch
- Department of Otorhinolaryngology, Hospital Clínico San Carlos, Complutense University, Madrid, Spain
| | - Gen Murakami
- Division of Internal Medicine, Jikou-kai Clinic of Home Visits, Sapporo, Japan
| | - Hiroshi Abe
- Akita University School of Medicine, Akita, Japan
| | - Yohei Honkura
- Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan
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Hansen LJ, Bloch SL, Frisch T, Sørensen MS. Distribution of microcrack surface density in the human otic capsule. Acta Otolaryngol 2021; 141:567-571. [PMID: 33825609 DOI: 10.1080/00016489.2021.1905875] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND The bony otic capsule is comprised of highly mineralized and dense compact bone. It is rarely remodelled and degenerative changes, therefore, accumulate around the inner ear. It is also a predilection site for the pathological remodelling seen in otosclerosis. Morphometric studies have documented increased numbers of dead osteocytes and microcracks in the human otic capsule. Microcracks may disrupt the lacuno-canalicular network and cause osteocyte apoptosis ultimately breaking up the perilabyrinthine bone signalling pathways and dynamics. This may be important to understand the pathogenesis of remodelling diseases like otosclerosis. AIMS/OBJECTIVES This study describes the spatial and regional distribution of microcrack surface density in relation to the inner ear and compares it to that previously recorded for otosclerosis. MATERIAL AND METHODS Forty-two temporal bones and five ribs were used. All samples were undecalcified, bulk stained in basic fuchsin and plastic embedded. Unbiased stereology was used to estimate the true surface density of microcracks (mm2/mm3) in perilabyrinthine bone. RESULTS The surface density of microcracks accumulates around the inner ear spaces, particularly in the lateral window regions, and increases with age. CONCLUSIONS AND SIGNIFICANCE This study documents the spatial and temporal association between microfractures and otosclerosis in the otic capsule.
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Affiliation(s)
- Lars Juul Hansen
- Otopathology Laboratory, Department of Otorhinolaryngology, Head and Neck Surgery and Audiology, University Hospital of Copenhagen, Rigshospitalet, Denmark
| | - Sune Land Bloch
- Otopathology Laboratory, Department of Otorhinolaryngology, Head and Neck Surgery and Audiology, University Hospital of Copenhagen, Rigshospitalet, Denmark
| | - Thomas Frisch
- Otopathology Laboratory, Department of Otorhinolaryngology, Head and Neck Surgery and Audiology, University Hospital of Copenhagen, Rigshospitalet, Denmark
| | - Mads Sølvsten Sørensen
- Otopathology Laboratory, Department of Otorhinolaryngology, Head and Neck Surgery and Audiology, University Hospital of Copenhagen, Rigshospitalet, Denmark
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Hansen LJ, Bloch SL, Frisch T, Sørensen MS. Microcrack surface density in the human otic capsule: An unbiased stereological quantification. Anat Rec (Hoboken) 2020; 304:961-967. [PMID: 33040475 DOI: 10.1002/ar.24535] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/06/2020] [Accepted: 08/14/2020] [Indexed: 11/07/2022]
Abstract
Bone is continuously remodeled to repair and strengthen degenerative bone with accumulating dead osteocytes and microfractures. Inner ear osteoprotegerin (OPG)-mediated inhibition of otic capsular bone remodeling causes excessive perilabyrinthine bone degeneration. Consequently, microcracks accumulate around the inner ear. Microcracks cause osteocyte apoptosis and may disrupt the canalicular network connecting osteocytes. Despite their linear microscopic appearance, microcracks are three-dimensional disruption planes and represent surface areas inside a tissue space. With an elevated microcrack burden the number of disconnected osteocytes is expected to increase. This may prove relevant to ongoing research in otic focal pathologies like otosclerosis. Therefore, an unbiased quantification of the microcrack surface density (mm2 /mm3 ) in the human otic capsule is essential. In this study unbiased stereology was applied to undecalcified bulk stained human temporal bones to demonstrate its feasibility in describing the three-dimensional reality behind two dimensional observations of microcracks. A total of 28 human temporal bones and five ribs were bulk stained in basic fuchsin, serially sectioned and hand-ground to a thickness of 80-120 μm. Both horizontal and vertical sections were produced and compared. This study showed that surface density of microcracks was significantly higher around the inner ear compared to ribs. Furthermore, no significant difference in microcrack surface density between horizontal and vertical sections in the temporal bone was demonstrated.
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Affiliation(s)
- Lars Juul Hansen
- Department of Otorhinolaryngology Head and Neck Surgery and Audiology, Otopathology Laboratory, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Sune Land Bloch
- Department of Otorhinolaryngology Head and Neck Surgery and Audiology, Otopathology Laboratory, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Thomas Frisch
- Department of Otorhinolaryngology Head and Neck Surgery and Audiology, Otopathology Laboratory, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Mads Sølvsten Sørensen
- Department of Otorhinolaryngology Head and Neck Surgery and Audiology, Otopathology Laboratory, University Hospital of Copenhagen, Copenhagen, Denmark
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Honkura Y, Hayashi S, Abe H, Murakami G, Rodríguez-Vázquez JF, Shibata S. The third vascular route of the inner ear or the canal of Cotugno: Its topographical anatomy, fetal development, and contribution to ossification of the otic capsule cartilage. Anat Rec (Hoboken) 2020; 304:872-882. [PMID: 32865892 DOI: 10.1002/ar.24508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/03/2020] [Accepted: 06/29/2020] [Indexed: 01/03/2023]
Abstract
Three vascular routes to the inner ear are known: (a) through the internal acoustic meatus with the vestibulocochlear nerve; (b) from the endolymphatic duct aperture; and (c) along the canal of Cotugno (CC) inserted into the vestibular part of the ear from the superior or brain side. The third is believed to contain only veins. Examinations of 33 human embryos and fetuses at 6-40 weeks demonstrated that (a) the CC appeared as a recess of epidural mesenchymal tissues at the superior aspect of the otic capsule cartilage in embryos and it was inserted deeply to issue multiple peripheral divisions inferolaterally and posteriorly at midterm; (b) the CC consistently passed through a ring of the superior or anterior semicircular canal and contained both, the arteries from the vestibulocochlear nerve origin at the midbrain and the vein draining into the sigmoid sinus or petrosal sinuses; and (c) the CC appeared not to contribute to ossification of the otic capsule cartilage but, after endochondral ossification of the internal ear, woven bone development occurred along a smooth interface of the CC with the ossified ear. In contrast, another interface between the developing bone and the residual cartilage of the otic capsule was rough and wavy with many short bony columns, called osseous globules. In addition, the endolymphatic duct accompanied veins but no arteries. Our results show that the CC is a major vascular route to the vestibular part of the otic capsule cartilage, but its role appears to be limited after ossification.
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Affiliation(s)
- Yohei Honkura
- Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Shogo Hayashi
- Department of Anatomy, School of Medicine, International University of Health and Welfare, Narita, Japan
| | - Hiroshi Abe
- Department of Anatomy, Akita University School of Medicine, Akita, Japan
| | - Gen Murakami
- Division of Internal Medicine, Jikou-kai Clinic of Home visits, Sapporo, Japan
| | | | - Shunichi Shibata
- Department of Maxillofacial Anatomy, Graduate School of Tokyo Medical and Dental University, Tokyo, Japan
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Quilhac A, de Ricqlès A, Lamrous H, Zylberberg L. Globuliosseiin the long limb bones ofPleurodeleswaltl(Amphibia, Urodela, Salamandridae). J Morphol 2014; 275:1226-37. [DOI: 10.1002/jmor.20296] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/04/2014] [Accepted: 05/15/2014] [Indexed: 01/14/2023]
Affiliation(s)
- Alexandra Quilhac
- Sorbonne Universités; UPMC Univ Paris 06; UMR 7193; Institut des Sciences de la Terre Paris (ISTeP), Equipe Biominéralisations et Environnements Sédimentaires; F-75005 Paris France
- CNRS, UMR 7193, Institut des Sciences de la Terre Paris (ISTeP); F-75005 Paris France
| | - Armand de Ricqlès
- Sorbonne Universités; UPMC Univ Paris 06; UMR 7193; Institut des Sciences de la Terre Paris (ISTeP), Equipe Biominéralisations et Environnements Sédimentaires; F-75005 Paris France
- CNRS, UMR 7193, Institut des Sciences de la Terre Paris (ISTeP); F-75005 Paris France
| | - Hayat Lamrous
- Sorbonne Universités; UPMC Univ Paris 06; UMR 7193; Institut des Sciences de la Terre Paris (ISTeP), Equipe Biominéralisations et Environnements Sédimentaires; F-75005 Paris France
- CNRS, UMR 7193, Institut des Sciences de la Terre Paris (ISTeP); F-75005 Paris France
| | - Louise Zylberberg
- Sorbonne Universités; UPMC Univ Paris 06; UMR 7193; Institut des Sciences de la Terre Paris (ISTeP), Equipe Biominéralisations et Environnements Sédimentaires; F-75005 Paris France
- CNRS, UMR 7193, Institut des Sciences de la Terre Paris (ISTeP); F-75005 Paris France
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Michaels L, Soucek S, Linthicum F. The intravestibular source of the vestibular aqueduct. II: its structure and function clarified by a developmental study of the intra-skeletal channels of the otic capsule. Acta Otolaryngol 2010; 130:420-8. [PMID: 19895329 DOI: 10.3109/00016480903253561] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION A developmental histologic study of the otic capsule indicates that it grows a system of lamellar bone with abundant interconnecting intraosseous channels. These include the 'cartilage canals' in the cartilage model, the chondro-osseous and Haversian-like (Volkmann's) canals in the ossified otic capsule, the fissula ante fenestram, which seems to function as a lifelong manufacturer of the latter two channels, and the inner layer (vestibular arch) of the vestibular aqueduct, which is a complex series of Volkmann's canals and microcanals. Chemical changes, possibly produced by breakdown of cells within the channels, may provide a homeostatic environment for the functions of hearing and balance that take place in the endolymphatic fluid. OBJECTIVES We studied the development of the otic capsule to clarify the cellular appearances that we had previously described in the normal vestibular arch and the changes in that structure in Ménière's disease. METHODS Step sections from 84 temporal bones, including those from fetuses, children and adults from a variety of ages were examined histologically. RESULTS Cartilage canals, bringing blood vessels and mesenchymal cells from perichondrium to the depths of the cartilage model to mediate ossification, are found early in fetal life and disappear when ossification is complete at about 24 weeks. The otic capsule is formed of chondro-osseous canals, which are composed of trabeculae of mineralized cartilage lacunae containing mesenchymal cells that undergo ossification (globuli ossei); also Volkmann's canals (like Haversian canals in long bones but multidirectional), which are produced from osteoblasts. The lumina of the latter frequently link up with chondro-osseous canals. Lamellar bone forms the background of the otic capsule. The fissula ante fenestram is present from early in the cartilage model and then throughout life. It appears to mediate bone production and the new formation of chondro-osseous channels and Volkmann's canals. The internal layer of the vestibular aqueduct (vestibular arch) is seen in the cartilage model of the otic capsule (present in early fetal life) as a vascular layer of perichondrally derived connective tissue (not cartilage) surrounding the endolymphatic duct. When endochondral ossification starts, the bone from the adjoining cochlear and vestibular sides embrace this connective tissue layer to form the outer bony layer of the vestibular aqueduct. Osteoblasts then fill the inner layer with lamellar bone and macro- and mini-Volkmann's canals. At 1 year osteoblasts in the walls of macro-Volkmann's canals, proliferating thereafter throughout life, produce large numbers of microcanals. It is possible that slow breakdown of these osteoblasts and of similar cells in the canals of the otic capsule proper may contribute to the homeostasis of the endolymphatic duct and that of the rest of the membranous labyrinth, respectively.
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Affiliation(s)
- Leslie Michaels
- University College London Ear Institute and Department of Cellular Pathology, UCL Medical School, University Street, London. UK.
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