Inner ear ossification and mineralization kinetics in human embryonic development - microtomographic and histomorphological study

Background Progressive transformation of the otic placode into the functional inner ear during gestational development in humans leads to the acquisition of hearing perception via the cochlea and balance and spatial orientation via the vestibular organ. Results Using a correlative approach involving micro-computerized tomography (micro-CT), transmission electron microscopy and histological techniques we were able to examine both the morphological and cellular changes associated with human inner ear development. Such an evaluation allowed for the examination of 3D geometry with high spatial and temporal resolution. In concert with gestational progression and growth of the cochlear duct, an increase in the distance between some of the Crista ampullaris is evident in all the specimens examined from GW12 to GW36. A parallel increase in the distances between the macular organs - fetal utricle and saccule - is also evident across the gestational stages examined. The distances between both the utricle and saccule to the three cristae ampullares also increased across the stages examined. A gradient in hair cell differentiation is apparent from apex to base of the fetal cochlea even at GW14. Conclusion We present structural information on human inner ear development across multiple levels of biological organization, including gross-morphology of the inner ear, cellular and subcellular details of hearing and vestibular organs, as well as ultrastructural details in the developing sensory epithelia. This enabled the gathering of detailed information regarding morphometric changes as well in realizing the complex developmental patterns of the human inner ear. We were able to quantify the volumetric and linear aspects of selected gestational inner ear specimens enabling a better understanding of the cellular changes across the fetal gestational timeline. Moreover, these data could serve as a reference for better understanding disorders that arise during inner ear development. Electronic supplementary material The online version of this article (10.1186/s12861-019-0191-y) contains supplementary material, which is available to authorized users.

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“…The cochlea attains near adult size by GW23. However, the differentiation process of the organ of Corti (OC) is completed by GW30 [13].…”

Section: Introductionmentioning

confidence: 99%

Growth and cellular patterning during fetal human inner ear development studied by a correlative imaging approach

et al. 2019

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“…Staining is only necessary when a researcher is interested in imaging soft tissue. Without staining, micro-CT provides great spatial resolution for high-density structures (e.g., orbit, humerus, femur) even if the structures are not completely ossified yet [20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Staining is performed by immersing the whole fetus or fetal organ in a staining solution.…”

Section: Stainingmentioning

confidence: 99%

Novel imaging techniques to study postmortem human fetal anatomy: a systematic review on microfocus-CT and ultra-high-field MRI

et al. 2019

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Background MRI and CT have been extensively used to study fetal anatomy for research and diagnostic purposes, enabling minimally invasive autopsy and giving insight in human fetal development. Novel (contrast-enhanced) microfocus CT (micro-CT) and ultra-high-field (≥ 7.0 T) MRI (UHF-MRI) techniques now enable micron-level resolution that combats the disadvantages of low-field MRI and conventional CT. Thereby, they might be suitable to study fetal anatomy in high detail and, in time, contribute to the postmortem diagnosis of fetal conditions. Objectives (1) To systematically examine the usability of micro-CT and UHF-MRI to study postmortem human fetal anatomy, and (2) to analyze factors that govern success at each step of the specimen preparation and imaging. Method MEDLINE and EMBASE were systematically searched to identify publications on fetal imaging by micro-CT or UHF-MRI. Scanning protocols were summarized and best practices concerning specimen preparation and imaging were enumerated. Results Thirty-two publications reporting on micro-CT and UHF-MRI were included. The majority of the publications focused on imaging organs separately and seven publications focused on whole body imaging, demonstrating the possibility of visualization of small anatomical structures with a resolution well below 100 μm. When imaging soft tissues by micro-CT, the fetus should be stained by immersion in Lugol's staining solution.Conclusion Micro-CT and UHF-MRI are both excellent imaging techniques to provide detailed images of gross anatomy of human fetuses. The present study offers an overview of the current best practices when using micro-CT and/or UHF-MRI to study fetal anatomy for clinical and research purposes. Key Points • Micro-CT and UHF-MRI can both be used to study postmortem human fetal anatomy for clinical and research purposes.• Micro-CT enables high-resolution imaging of fetal specimens in relatively short scanning time. However, tissue staining using a contrast solution is necessary to enable soft-tissue visualization. • UHF-MRI enables high-resolution imaging of fetal specimens, without the necessity of prior staining, but with the drawback of long scanning time.

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“…The malleus and incus develop from the proximal end of Meckel's cartilage, a rod of cartilaginous tissue that forms from the first pharyngeal arch. Both of these ossicles transform from cartilage to bone by endochondral ossification during weeks 19-24 of human gestation (Richard et al, 2017) and approximately E14.5 in the mouse (Anthwal et al, 2013). Most of the stapes, except for a mesoderm-derived portion of the footplate that contacts the oval window, develops from Reichert's cartilage comprised of NCCs of the second pharyngeal arch.…”

Section: Ossiclesmentioning

confidence: 99%

Neural crest contributions to the ear: Implications for congenital hearing disorders

Martin

2019

Hearing Research

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Congenital hearing disorders affect millions of children worldwide and can significantly impact acquisition of speech and language. Efforts to identify the developmental genetic etiologies of conductive and sensorineural hearing losses have revealed critical roles for cranial neural crest cells (NCCs) in ear development. Cranial NCCs contribute to all portions of the ear, and defects in neural crest development can lead to neurocristopathies associated with profound hearing loss. The molecular mechanisms governing the development of neural crest derivatives within the ear are partially understood, but many questions remain. In this review, we describe recent advancements in determining neural crest contributions to the ear, how they inform our understanding of neurocristopathies, and highlight new avenues for further research using bioinformatic approaches.

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Inner ear ossification and mineralization kinetics in human embryonic development - microtomographic and histomorphological study

Cited by 27 publications

References 50 publications

Growth and cellular patterning during fetal human inner ear development studied by a correlative imaging approach

Growth and cellular patterning during fetal human inner ear development studied by a correlative imaging approach

Novel imaging techniques to study postmortem human fetal anatomy: a systematic review on microfocus-CT and ultra-high-field MRI

Neural crest contributions to the ear: Implications for congenital hearing disorders

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