1
|
Kumar P, Sharma S, Kaur C, Pal I, Bhardwaj DN, Nag TC, Roy TS, Jacob TG. Nerve fibre morphometry with transmission electron microscopy: Application of the nucleator probe in ImageJ. MethodsX 2023; 10:102085. [PMID: 36926271 PMCID: PMC10011813 DOI: 10.1016/j.mex.2023.102085] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 02/18/2023] [Indexed: 03/05/2023] Open
Abstract
Stereology and semiautomated binary image histomorphometry are two common methods used for morphometry of nerve fibres. Nucleator probe can be used for the estimation of morphometric parameters like diameter, perimeter, area and volume of a structure that is approximately either a circle or a sphere. In this study, we estimated these parameters with the help of ImageJ software on calibrated transmission electron micrographs. We procured samples of the cochlear nerve (CN) during winter months, within 6-12 hours of death, to reduce post-mortem autolytic changes. The temporal bones containing the CN were fixed by immersion in chilled paraformaldehyde. After dissecting out from the petrous part of the temporal bone, the CN were osmicated and processed for embedding in resin. From the resin blocks, silver coloured (70 nm) ultrathin sections were cut and picked on 300-mesh copper grids, stained with uranyl acetate and lead citrate and viewed under Tecnai G2-20 transmission electron microscope. The transmission electron micrographs had scale bars embedded into them by the software at the time of imaging, and the morphometric parameters of randomly selected nerve fibres were measured using the ImageJ software. The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.•Nucleator probe is used for the estimation of morphometric parameters like diameter, perimeter, area or volume•Morphometric parameters were estimated by the ImageJ software on calibrated transmission electron micrographs•The ImageJ software could become a low-cost and dependable tool for nerve fibre morphometry.
Collapse
Key Words
- Application of the nucleator probe with ImageJ
- Axon
- CN, cochlear nerve
- DDSA, Dodecenyl Succinic Anhydride
- DDW, double distilled water
- DMP-30, 2,4,6- Tri (dimethylaminomethyl) Phenol-30
- IAM, internal acoustic meatus: M, myelin
- MNA, Methyl Nadic Anhydride
- Myelin
- PB, phosphate buffer
- RT, room temperature
- Stereology
- axe, axon
Collapse
Affiliation(s)
- Punit Kumar
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Saroj Sharma
- Department of Anatomy, Dr. Baba Saheb Ambedkar Medical College & Hospital, Delhi, India
| | - Charanjeet Kaur
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Dept of Otolaryngology-Head and Neck Surgery, Harvard Medical School, Massachusetts Eye and Ear, Boston, MA, United States
| | - Indra Pal
- Department of Neurobiology School of Medicine, University of Pittsburgh, Pittsburgh, PA, United States
| | - Daya Nand Bhardwaj
- Department of Forensic Medicine & Toxicology, All India Institute of Medical Sciences, New Delhi, India
| | - Tapas Chandra Nag
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| | - Tara Sankar Roy
- Department of Anatomy, North DMC Medical College & Hindu Rao Hospital, New Delhi, India
| | - Tony George Jacob
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India
| |
Collapse
|
2
|
The ultrastructural study of human cochlear nerve at different ages. Hear Res 2022; 416:108443. [DOI: 10.1016/j.heares.2022.108443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/11/2022] [Accepted: 01/16/2022] [Indexed: 11/21/2022]
|
3
|
Mishra S, Roy T, Saini S. Development of the hair cells of the human cochlea: A scanning electron microscopic study. J Microsc Ultrastruct 2022; 11:17-22. [PMID: 37144166 PMCID: PMC10153736 DOI: 10.4103/jmau.jmau_107_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 11/26/2020] [Accepted: 12/01/2020] [Indexed: 11/04/2022] Open
Abstract
Introduction In the mammalian auditory system, the cochlea is the first to attain structural and functional maturity. Although ultrastructural details of the developing cochlea of lower animals have been elucidated in the last few decades, comprehensive studies on human cochlea are lacking. Materials and Methods In the present investigation we studied the development and maturation of the hair cells of ten human fetal cochlea from gestational weeks (GW) 12 to 37 by scanning electron microscopy. Result We observed undifferentiated hair cells possessing numerous surface projections and long kinocilium during GW 14. At GW16, the primitive hair cells were arranged in one inner and four outer rows and had globular apices indicating the initiation of stereocilia formation. By GW 22, the globular apices were replaced by linear stereocilia and occasional kinocillia. Mature hair cells with sterocilia were observed in the basal turn at 30th week of gestation. At GW 37, the stereocilia were arranged in a typical "V" shaped pattern at the middle and apical coil, while the stereocilia of the basal turn were shorter in length resembling the adult cochlea. The inner hair cells were long and slender while outer hair cells were pear shaped, kinocilium were absent and the tunnel of Corti were well formed. Conclusion It is concluded that in human, the morphological maturation of the hair cells starts in the basal turn around GW 22 and continues till 37th week in the apical turn indicating that early maturation of the cochlea may have a role on development of the higher auditory pathway connections.
Collapse
|
4
|
Stojkovic M, Han D, Jeong M, Stojkovic P, Stankovic KM. Human induced pluripotent stem cells and CRISPR/Cas-mediated targeted genome editing: Platforms to tackle sensorineural hearing loss. STEM CELLS (DAYTON, OHIO) 2021; 39:673-696. [PMID: 33586253 DOI: 10.1002/stem.3353] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 12/13/2020] [Indexed: 11/09/2022]
Abstract
Hearing loss (HL) is a major global health problem of pandemic proportions. The most common type of HL is sensorineural hearing loss (SNHL) which typically occurs when cells within the inner ear are damaged. Human induced pluripotent stem cells (hiPSCs) can be generated from any individual including those who suffer from different types of HL. The development of new differentiation protocols to obtain cells of the inner ear including hair cells (HCs) and spiral ganglion neurons (SGNs) promises to expedite cell-based therapy and screening of potential pharmacologic and genetic therapies using human models. Considering age-related, acoustic, ototoxic, and genetic insults which are the most frequent causes of irreversible damage of HCs and SGNs, new methods of genome editing (GE), especially the CRISPR/Cas9 technology, could bring additional opportunities to understand the pathogenesis of human SNHL and identify novel therapies. However, important challenges associated with both hiPSCs and GE need to be overcome before scientific discoveries are correctly translated to effective and patient-safe applications. The purpose of the present review is (a) to summarize the findings from published reports utilizing hiPSCs for studies of SNHL, hence complementing recent reviews focused on animal studies, and (b) to outline promising future directions for deciphering SNHL using disruptive molecular and genomic technologies.
Collapse
Affiliation(s)
- Miodrag Stojkovic
- Eaton Peabody Laboratories, Department of Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, USA.,Department of Otolaryngology Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Dongjun Han
- Eaton Peabody Laboratories, Department of Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, USA.,Department of Otolaryngology Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Minjin Jeong
- Eaton Peabody Laboratories, Department of Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, USA.,Department of Otolaryngology Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Petra Stojkovic
- Eaton Peabody Laboratories, Department of Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, USA.,Department of Otolaryngology Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, USA
| | - Konstantina M Stankovic
- Eaton Peabody Laboratories, Department of Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear, Boston, Massachusetts, USA.,Department of Otolaryngology Head and Neck Surgery, Harvard Medical School, Boston, Massachusetts, USA.,Program in Speech and Hearing Bioscience and Technology, Harvard University, Cambridge, Massachusetts, USA.,Harvard Program in Therapeutic Science, Harvard Medical School, Boston, Massachusetts, USA.,Harvard Stem Cell Institute, Cambridge, Massachusetts, USA
| |
Collapse
|
5
|
Kohrman DC, Borges BC, Cassinotti LR, Ji L, Corfas G. Axon-glia interactions in the ascending auditory system. Dev Neurobiol 2021; 81:546-567. [PMID: 33561889 DOI: 10.1002/dneu.22813] [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: 06/11/2020] [Revised: 11/25/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022]
Abstract
The auditory system detects and encodes sound information with high precision to provide a high-fidelity representation of the environment and communication. In mammals, detection occurs in the peripheral sensory organ (the cochlea) containing specialized mechanosensory cells (hair cells) that initiate the conversion of sound-generated vibrations into action potentials in the auditory nerve. Neural activity in the auditory nerve encodes information regarding the intensity and frequency of sound stimuli, which is transmitted to the auditory cortex through the ascending neural pathways. Glial cells are critical for precise control of neural conduction and synaptic transmission throughout the pathway, allowing for the precise detection of the timing, frequency, and intensity of sound signals, including the sub-millisecond temporal fidelity is necessary for tasks such as sound localization, and in humans, for processing complex sounds including speech and music. In this review, we focus on glia and glia-like cells that interact with hair cells and neurons in the ascending auditory pathway and contribute to the development, maintenance, and modulation of neural circuits and transmission in the auditory system. We also discuss the molecular mechanisms of these interactions, their impact on hearing and on auditory dysfunction associated with pathologies of each cell type.
Collapse
Affiliation(s)
- David C Kohrman
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Beatriz C Borges
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Luis R Cassinotti
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Lingchao Ji
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Gabriel Corfas
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
6
|
Goldberg E, McKenzie CA, de Vrijer B, Eagleson R, de Ribaupierre S. Fetal Response to a Maternal Internal Auditory Stimulus. J Magn Reson Imaging 2020; 52:139-145. [PMID: 31951084 DOI: 10.1002/jmri.27033] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/06/2019] [Accepted: 12/11/2019] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Functional MRI (fMRI) is a noninvasive method to investigate the neural correlates of brain development. Insight into the rapidly developing brain in utero is limited, and fetal fMRI can be used to gain a greater understanding of the developmental process. Fetal brain fMRI is typically limited to resting-state fMRI due to the difficulty to instruct or provide a stimulus to the fetus. Previous studies have employed auditory task fMRI with an external sound stimulus directly on the abdomen of the mother; however, this practice has since been deemed unsafe for the developing fetus. PURPOSE To investigate a reliable and safe paradigm to study the development of fetal brain networks, we postulated that an internal task, such as the mother's singing, as the auditory stimulus would result in activation in the fetal primary auditory cortex. STUDY TYPE Cohort. POPULATION Pregnant women with singleton pregnancies (n = 9; 33-38 weeks gestational age). FIELD STRENGTH/SEQUENCE All subjects underwent two task-based block design blood oxygen level-dependent (BOLD) at 1.5T or 3T. ASSESSMENT Each volume was assessed for fetal motion and manually reoriented and realigned to correct for fetal motion. Once the motion was corrected, a gestational age-matched parcellated atlas with regions of interest overlaid onto the activation map was used to determine which regions in the brain had activation during task phases. STATISTICAL TESTS First Level Analysis. MRI data were analyzed using SPM 12 as a task fMRI. RESULTS Eight subjects had activation on the right Heschl's gyrus; six fetuses demonstrated activation on the left when exposed to the internal acoustic stimulus. Additionally, activation was found on the right and left middle cingulate cortex (MCC) and the left putamen. DATA CONCLUSION Maternal singing can be used as an internal stimulus to activate the auditory network and Heschl's gyrus during fetal fMRI. Level of Evidence 2 Technical Efficacy Stage 2 J. Magn. Reson. Imaging 2020;52:139-145.
Collapse
Affiliation(s)
- Estee Goldberg
- Biomedical Engineering, Western University, London, Ontario, Canada
| | - Charles A McKenzie
- Biomedical Engineering, Western University, London, Ontario, Canada.,Medical Biophysics, Western University, London, Ontario, Canada.,Children's Health Research Institute, Western University, London, Ontario, Canada
| | - Barbra de Vrijer
- Children's Health Research Institute, Western University, London, Ontario, Canada.,Department of Obstetrics and Gynaecology, Western University, London, Ontario, Canada
| | - Roy Eagleson
- Biomedical Engineering, Western University, London, Ontario, Canada.,Brain and Mind Institute, Professor of Engineering, Western University, London, Ontario, Canada
| | - Sandrine de Ribaupierre
- Biomedical Engineering, Western University, London, Ontario, Canada.,Medical Biophysics, Western University, London, Ontario, Canada.,Children's Health Research Institute, Western University, London, Ontario, Canada.,Brain and Mind Institute, Professor of Engineering, Western University, London, Ontario, Canada.,Department of Clinical Neurological Sciences, Western University, London, Ontario, Canada
| |
Collapse
|
7
|
Kaur C, Saini S, Pal I, Kumar P, Chandra Sati H, Jacob TG, Bhardwaj DN, Roy TS. Age-related changes in the number of cresyl-violet-stained, parvalbumin and NMDAR 2B expressing neurons in the human spiral ganglion. Hear Res 2020; 388:107883. [PMID: 31981822 DOI: 10.1016/j.heares.2020.107883] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/12/2019] [Accepted: 12/31/2019] [Indexed: 01/11/2023]
Abstract
Animal-studies associate age-related hearing loss (presbycusis) with decreasing number of spiral ganglion neurons (SGNs) in Rosenthal's canal (RC) of cochlea. The excitatory neurotransmitter for SGNs is glutamate (through its receptor NMDAR 2B), which can be neurotoxic through Ca2+ overload. Neurotoxicity is balanced by calcium-binding proteins (CBPs) like Parvalbumin (PV), which is the predominant CBP of the SGNs. To estimate the volume of the RC and total number of SGNs that are immunoreactive to PV and NMDAR 2B, we used unbiased stereology in 35 human cochleae derived from cadavers of persons from 2nd to 8th decade of life (subsequently statistically divided into two groups) and compared them to the total number of cresyl violet (CV) stained SGNs. We also estimated the volume of individual neurons and their nuclei. Regression analysis was made on estimated parameters against age. Hierarchical-cluster analysis was done on the neuronal against neuronal nuclear volumes.The average volume of the RC did not change with increasing age (p = 0.4115). The total number of SGNs (CV-stained and those separately expressing PV and NMDAR 2B) significantly decreased with age (p < 0.001). We identified three distinct populations of neurons on the basis of their volumes among SGNs. Thus, there is significant age-related decline in the total number of SGNs, which starts early in life. It may be due to ambient noise and inadequate neutralisation of excitotoxicity.
Collapse
Affiliation(s)
- Charanjeet Kaur
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Shubhi Saini
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Indra Pal
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Punit Kumar
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Hem Chandra Sati
- Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Tony George Jacob
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Daya Nand Bhardwaj
- Department of Forensic Medicine and Toxicology, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Tara Sankar Roy
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi, 110029, India.
| |
Collapse
|
8
|
Novel insights into inner ear development and regeneration for targeted hearing loss therapies. Hear Res 2019; 397:107859. [PMID: 31810596 DOI: 10.1016/j.heares.2019.107859] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/06/2019] [Accepted: 11/25/2019] [Indexed: 02/06/2023]
Abstract
Sensorineural hearing loss is the most common sensory deficit in humans. Despite the global scale of the problem, only limited treatment options are available today. The mammalian inner ear is a highly specialized postmitotic organ, which lacks proliferative or regenerative capacity. Since the discovery of hair cell regeneration in non-mammalian species however, much attention has been placed on identifying possible strategies to reactivate similar responses in humans. The development of successful regenerative approaches for hearing loss strongly depends on a detailed understanding of the mechanisms that control human inner ear cellular specification, differentiation and function, as well as on the development of robust in vitro cellular assays, based on human inner ear cells, to study these processes and optimize therapeutic interventions. We summarize here some aspects of inner ear development and strategies to induce regeneration that have been investigated in rodents. Moreover, we discuss recent findings in human inner ear development and compare the results with findings from animal models. Finally, we provide an overview of strategies for in vitro generation of human sensory cells from pluripotent and somatic progenitors that may provide a platform for drug development and validation of therapeutic strategies in vitro.
Collapse
|
9
|
Saini S, Kaur C, Pal I, Kumar P, Jacob TG, Thakar A, Roy KK, Roy TS. Morphological development of the human cochlear nucleus. Hear Res 2019; 382:107784. [DOI: 10.1016/j.heares.2019.107784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/19/2019] [Accepted: 08/15/2019] [Indexed: 11/29/2022]
|
10
|
β-Secretase BACE1 Is Required for Normal Cochlear Function. J Neurosci 2019; 39:9013-9027. [PMID: 31527119 DOI: 10.1523/jneurosci.0028-19.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 08/30/2019] [Accepted: 09/04/2019] [Indexed: 12/20/2022] Open
Abstract
Cleavage of amyloid precursor protein (APP) by β-secretase BACE1 initiates the production and accumulation of neurotoxic amyloid-β peptides, which is widely considered an essential pathogenic mechanism in Alzheimer's disease (AD). Here, we report that BACE1 is essential for normal auditory function. Compared with wild-type littermates, BACE1-/- mice of either sex exhibit significant hearing deficits, as indicated by increased thresholds and reduced amplitudes in auditory brainstem responses (ABRs) and decreased distortion product otoacoustic emissions (DPOAEs). Immunohistochemistry revealed aberrant synaptic organization in the cochlea and hypomyelination of auditory nerve fibers as predominant neuropathological substrates of hearing loss in BACE1-/- mice. In particular, we found that fibers of spiral ganglion neurons (SGN) close to the organ of Corti are disorganized and abnormally swollen. BACE1 deficiency also engenders organization defects in the postsynaptic compartment of SGN fibers with ectopic overexpression of PSD95 far outside the synaptic region. During postnatal development, auditory fiber myelination in BACE1-/- mice lags behind dramatically and remains incomplete into adulthood. We relate the marked hypomyelination to the impaired processing of Neuregulin-1 when BACE1 is absent. To determine whether the cochlea of adult wild-type mice is susceptible to AD treatment-like suppression of BACE1, we administered the established BACE1 inhibitor NB-360 for 6 weeks. The drug suppressed BACE1 activity in the brain, but did not impair hearing performance and, upon neuropathological examination, did not produce the characteristic cochlear abnormalities of BACE1-/- mice. Together, these data strongly suggest that the hearing loss of BACE1 knock-out mice represents a developmental phenotype.SIGNIFICANCE STATEMENT Given its crucial role in the pathogenesis of Alzheimer's disease (AD), BACE1 is a prime pharmacological target for AD prevention and therapy. However, the safe and long-term administration of BACE1-inhibitors as envisioned in AD requires a comprehensive understanding of the various physiological functions of BACE1. Here, we report that BACE1 is essential for the processing of auditory signals in the inner ear, as BACE1-deficient mice exhibit significant hearing loss. We relate this deficit to impaired myelination and aberrant synapse formation in the cochlea, which manifest during postnatal development. By contrast, prolonged pharmacological suppression of BACE1 activity in adult wild-type mice did not reproduce the hearing deficit or the cochlear abnormalities of BACE1 null mice.
Collapse
|
11
|
Kaur C, Pal I, Saini S, Jacob T, Nag T, Thakar A, Bhardwaj D, Roy T. Comparison of unbiased stereological estimation of total number of cresyl violet stained neurons and parvalbumin positive neurons in the adult human spiral ganglion. J Chem Neuroanat 2018. [DOI: 10.1016/j.jchemneu.2017.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
12
|
Mishra S, Roy TS, Wadhwa S. Morphological and morphometrical maturation of ventral cochlear nucleus in human foetus. J Chem Neuroanat 2017; 93:38-47. [PMID: 28341180 DOI: 10.1016/j.jchemneu.2017.03.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 03/06/2017] [Accepted: 03/16/2017] [Indexed: 11/15/2022]
Abstract
Auditory impulses perceived by the hair cells of the organ of corti are relayed in the cochlear nucleus, the first relay station in the brainstem, by the cochlear nerve. The human foetus is well known to respond to sound during the last trimester of gestation. On the contrary, studies conducted in rat, cat and mouse have shown that these mammals have an immature auditory system at the time of birth. There are very few reports available regarding the morphological and functional maturation of the cochlear nucleus in human. Although the human cochlear nucleus neurons attain adult morphological characters by mid-gestation, there are hardly any studies discussing the functional maturation of the cochlear nucleus. Hence the present study was aimed at observing the morphological as well as functional maturation of the human foetal cochlear nuclei at various gestational ages. Morphological maturation was observed qualitatively while stereological estimation of the volume of well defined ventral cochlear nucleus (VCN) was calculated by the Cavalieri principle; neuronal count and density was estimated by dissector principle. The functional maturation was assessed by observing the expression of synaptophysin, a synaptic marker, at different gestational ages and by the presence of parvalbumin, a calcium binding functional neuronal marker by immunohistochemistry. Neurons showed coarse Nissl's substance and well developed cell processes and gradual increase in cell size by the 24th-30th gestational week. Synaptophysin labeling in the complete cochlear nucleus was observed at 20 weeks of gestation. Adult pattern of synaptophysin labeling was observed finally at37weeks of gestation. Earliest presence of parvalbumin expression was detected at 16 weeks of gestation and a distinct adult pattern was seen at 37 weeks of gestation. This study concluded that morphological and functional maturation of the human cochlear nuclei occurs simultaneously during mid-gestation which represents the critical period of development and continues up to term.
Collapse
Affiliation(s)
- Sabita Mishra
- All India Institute of Medical Sciences, New Delhi, India.
| | - T S Roy
- All India Institute of Medical Sciences, New Delhi, India
| | - Shashi Wadhwa
- All India Institute of Medical Sciences, New Delhi, India
| |
Collapse
|
13
|
Degeneration of auditory nerve fibers in guinea pigs with severe sensorineural hearing loss. Hear Res 2017; 345:79-87. [DOI: 10.1016/j.heares.2017.01.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 12/07/2016] [Accepted: 01/06/2017] [Indexed: 01/17/2023]
|
14
|
Lim R, Brichta AM. Anatomical and physiological development of the human inner ear. Hear Res 2016; 338:9-21. [PMID: 26900072 DOI: 10.1016/j.heares.2016.02.004] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 01/20/2016] [Accepted: 02/12/2016] [Indexed: 01/05/2023]
Abstract
We describe the development of the human inner ear with the invagination of the otic vesicle at 4 weeks gestation (WG), the growth of the semicircular canals from 5 WG, and the elongation and coiling of the cochlea at 10 WG. As the membranous labyrinth takes shape, there is a concomitant development of the sensory neuroepithelia and their associated structures within. This review details the growth and differentiation of the vestibular and auditory neuroepithelia, including synaptogenesis, the expression of stereocilia and kinocilia, and innervation of hair cells by afferent and efferent nerve fibres. Along with development of essential sensory structures we outline the formation of crucial accessory structures of the vestibular system - the cupula and otolithic membrane and otoconia as well as the three cochlea compartments and the tectorial membrane. Recent molecular studies have elaborated on classical anatomical studies to characterize the development of prosensory and sensory regions of the fetal human cochlea using the transcription factors, PAX2, MAF-B, SOX2, and SOX9. Further advances are being made with recent physiological studies that are beginning to describe when hair cells become functionally active during human gestation. This article is part of a Special Issue entitled <Annual Reviews 2016>.
Collapse
Affiliation(s)
- Rebecca Lim
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, The University of Newcastle, NSW, Australia.
| | - Alan M Brichta
- School of Biomedical Sciences and Pharmacy, Faculty of Health and Medicine, The University of Newcastle, NSW, Australia
| |
Collapse
|
15
|
Sharma S, Ray B, Dinda A, Roy T. Cochleotopy of human cochlear nucleus. J ANAT SOC INDIA 2015. [DOI: 10.1016/j.jasi.2015.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
16
|
Xie B, Dai C, Li H. Attenuated infrared neuron stimulation response in cochlea of deaf animals may associate with the degeneration of spiral ganglion neurons. BIOMEDICAL OPTICS EXPRESS 2015; 6:1990-2005. [PMID: 26114024 PMCID: PMC4473739 DOI: 10.1364/boe.6.001990] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 04/23/2015] [Accepted: 04/24/2015] [Indexed: 05/13/2023]
Abstract
HYPOTHESIS We hypothesize that degenerated spiral ganglion neurons (SGNs) in guinea pigs reduces auditory brainstem responses evoked by pulsed infrared stimulation. BACKGROUND Pulsed infrared laser excitation can directly evoke physiological responses in neuronal and other excitable cells in vivo and in vitro. Laser pulses could benefit patients with cochlear implants to stimulate the auditory system. METHODS Pulsed infrared lasers were used to study evoked optical auditory brainstem responses (oABRs) in normal hearing and deafened animals. Aslo, the morphology and anatomy of SGNs in normal hearing and deafened guinea pigs were compared. RESULTS By recording oABRs evoked by varying infrared laser pulse durations, it is suggested that degeneration of SGNs in deafened guinea pigs was associated with an elevated oABR threshold and with lower amplitudes. Moreover, oABR threshold decreased while amplitudes increased in both normal hearing and deafened animals as the pulse duration prolonged. Electron microscopy revealed that SGNs in deafened guinea pigs had swollen and vacuolar mitochondria, as well as demyelinated soma and axons. CONCLUSION Infrared laser pulses can stimulate SGNs to evoke oABRs in guinea pigs. Deafened guinea pigs have elevated thresholds and smaller amplitude responses, likely a result of degenerated SGNs. Short pulse durations are more suitable to evoke responses in both normal hearing and deafened animals.
Collapse
Affiliation(s)
- Bingbin Xie
- Department of Otology and Skull Base Surgery, Hearing Research Key Lab of Health Ministry of China, Eye and ENT Hospital, Fudan University, Shanghai, 200031, China
| | - Chunfu Dai
- Department of Otology and Skull Base Surgery, Hearing Research Key Lab of Health Ministry of China, Eye and ENT Hospital, Fudan University, Shanghai, 200031, China ;
| | - Huawei Li
- Department of Otology and Skull Base Surgery, Hearing Research Key Lab of Health Ministry of China, Eye and ENT Hospital, Fudan University, Shanghai, 200031, China ;
| |
Collapse
|
17
|
Ramkumar M, Sharma S, Jacob TG, Bhardwaj DN, Nag TC, Roy TS. The human trochlear and abducens nerves at different ages - a morphometric study. Aging Dis 2015; 6:6-16. [PMID: 25657848 DOI: 10.14336/ad.2014.0310] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 02/21/2014] [Accepted: 03/10/2014] [Indexed: 11/01/2022] Open
Abstract
The trochlear and abducens nerves (TN and AN) control the movement of the superior oblique and lateral rectus muscles of the eyeball, respectively. Despite their immense clinical and radiological importance no morphometric data was available from a wide spectrum of age groups for comparison with either pathological or other conditions involving these nerves. In the present study, morphometry of the TN and AN was performed on twenty post-mortem samples ranging from 12-90 years of age. The nerve samples were processed for resin embedding and toluidine blue stained thin (1µm) sections were used for estimating the total number of myelinated axons by fractionator and the cross sectional area of the nerve and the axons by point counting methods. We observed that the TN was covered by a well-defined epineurium and had ill-defined fascicles, whereas the AN had multiple fascicles with scanty epineurium. Both nerves contained myelinated and unmyelinated fibers of various sizes intermingled with each other. Out of the four age groups (12-20y, 21-40y, 41-60y and >61y) the younger groups revealed isolated bundles of small thinly myelinated axons. The total number of myelinated fibers in the TN and AN at various ages ranged from 1100-3000 and 1600-7000, respectively. There was no significant change in the cross-sectional area of the nerves or the axonal area of the myelinated nerves across the age groups. However, myelin thickness increased significantly in the AN with aging (one way ANOVA). The present study provides baseline morphometric data on the human TN and AN at various ages.
Collapse
Affiliation(s)
- Muthu Ramkumar
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi-110608, India
| | - Saroj Sharma
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi-110608, India
| | - Tony G Jacob
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi-110608, India
| | - Daya N Bhardwaj
- Department of Forensic Medicine, All India Institute of Medical Sciences, New Delhi-110608, India
| | - Tapas C Nag
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi-110608, India
| | - Tara Sankar Roy
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi-110608, India
| |
Collapse
|
18
|
Sharma S, Nag T, Bhardwaj D, Vanamail P, Roy T. Changing population of neurons and glia in the human cochlear nucleus with progressive age – A stereological study. J ANAT SOC INDIA 2014. [DOI: 10.1016/j.jasi.2014.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
19
|
Locher H, de Groot JCMJ, van Iperen L, Huisman MA, Frijns JHM, Chuva de Sousa Lopes SM. Distribution and development of peripheral glial cells in the human fetal cochlea. PLoS One 2014; 9:e88066. [PMID: 24498246 PMCID: PMC3909285 DOI: 10.1371/journal.pone.0088066] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 01/03/2014] [Indexed: 11/18/2022] Open
Abstract
The adult human cochlea contains various types of peripheral glial cells that envelop or myelinate the three different domains of the spiral ganglion neurons: the central processes in the cochlear nerve, the cell bodies in the spiral ganglia, and the peripheral processes in the osseous spiral lamina. Little is known about the distribution, lineage separation and maturation of these peripheral glial cells in the human fetal cochlea. In the current study, we observed peripheral glial cells expressing SOX10, SOX9 and S100B as early as 9 weeks of gestation (W9) in all three neuronal domains. We propose that these cells are the common precursor to both mature Schwann cells and satellite glial cells. Additionally, the peripheral glial cells located along the peripheral processes expressed NGFR, indicating a phenotype distinct from the peripheral glial cells located along the central processes. From W12, the spiral ganglion was gradually populated by satellite glial cells in a spatiotemporal gradient. In the cochlear nerve, radial sorting was accomplished by W22 and myelination started prior to myelination of the peripheral processes. The developmental dynamics of the peripheral glial cells in the human fetal cochlea is in support of a neural crest origin. Our study provides the first overview of the distribution and maturation of peripheral glial cells in the human fetal cochlea from W9 to W22.
Collapse
Affiliation(s)
- Heiko Locher
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
- Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, the Netherlands
| | - John C. M. J. de Groot
- Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, the Netherlands
| | - Liesbeth van Iperen
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
| | - Margriet A. Huisman
- Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, the Netherlands
| | - Johan H. M. Frijns
- Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, the Netherlands
| | - Susana M. Chuva de Sousa Lopes
- Department of Anatomy and Embryology, Leiden University Medical Center, Leiden, the Netherlands
- Department for Reproductive Medicine, Ghent University Hospital, Ghent, Belgium
- * E-mail:
| |
Collapse
|
20
|
Functional plasticity before the cradle: a review of neural functional imaging in the human fetus. Neurosci Biobehav Rev 2013; 37:2220-32. [PMID: 23542738 DOI: 10.1016/j.neubiorev.2013.03.013] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Revised: 03/13/2013] [Accepted: 03/20/2013] [Indexed: 01/17/2023]
Abstract
The organization of the brain is highly plastic in fetal life. Establishment of healthy neural functional systems during the fetal period is essential to normal growth and development. Across the last several decades, remarkable progress has been made in understanding the development of human fetal functional brain systems. This is largely due to advances in imaging methodologies. Fetal neuroimaging began in the 1950-1970's with fetal electroencephalography (EEG) applied during labor. Later, in the 1980's, magnetoencephalography (MEG) emerged as an effective approach for investigating fetal brain function. Most recently, functional magnetic resonance imaging (fMRI) has arisen as an additional powerful approach for examining fetal brain function. This review will discuss major developmental findings from fetal imaging studies such as the maturation of prenatal sensory system functions, functional hemispheric asymmetry, and sensory-driven neurodevelopment. We describe how with improved imaging and analysis techniques, functional imaging of the fetus has the potential to assess the earliest point of neural maturation and provide insight into the patterning and sequence of normal and abnormal brain development.
Collapse
|
21
|
Kim JH, Rodríguez-Vázquez JF, Verdugo-López S, Cho KH, Murakami G, Cho BH. Early Fetal Development of the Human Cochlea. Anat Rec (Hoboken) 2011; 294:996-1002. [DOI: 10.1002/ar.21387] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 03/03/2011] [Indexed: 11/06/2022]
|
22
|
Time sequence of auditory nerve and spiral ganglion cell degeneration following chronic kanamycin-induced deafness in the guinea pig. Brain Res 2010; 1331:28-38. [DOI: 10.1016/j.brainres.2010.02.058] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2009] [Revised: 02/07/2010] [Accepted: 02/19/2010] [Indexed: 02/06/2023]
|
23
|
Temporal distribution of mRNA expression levels of various genes in the developing human inferior colliculus. Neurosci Lett 2009; 461:229-34. [DOI: 10.1016/j.neulet.2009.06.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Revised: 05/27/2009] [Accepted: 06/08/2009] [Indexed: 01/01/2023]
|
24
|
DeCasper AJ, Prescott P. Lateralized processes constrain auditory reinforcement in human newborns. Hear Res 2009; 255:135-41. [DOI: 10.1016/j.heares.2009.06.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 06/18/2009] [Accepted: 06/24/2009] [Indexed: 11/26/2022]
|
25
|
Age changes in the human oculomotor nerve - a stereological study. Ann Anat 2009; 191:260-6. [PMID: 19406628 DOI: 10.1016/j.aanat.2009.02.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 11/25/2008] [Accepted: 02/10/2009] [Indexed: 10/20/2022]
Abstract
The oculomotor nerve (ON) provides motor innervation to the eyeball and exhibits alterations in various physiological and pathological conditions, which may result in abnormal ocular movement. Although the nerve has been studied in detail, very few data are available regarding its morphology and changes with aging. Hence, in the present investigation, the neural and connective tissue organizations of the pre-cavernous part of the ON were studied in order to provide sequential data regarding age-related morphological changes. Thirty-eight ON from cadavers aged from 40 post-natal days to 78 years were studied. Cross-sections of the nerve revealed a poorly defined multifascicular arrangement with predominant myelinated fibres of various calibres randomly intermingled with unmyelinated fibres. Small- and medium-sized fibres (probably parasympathetic) were mainly located at the junction of the central and the paracentral zones of the nerves. Using unbiased stereological techniques, the total number of the axons, the area of the myelinated fibres and myelin sheath thickness were estimated. The cross-sectional area of the nerve increased significantly up to the third decade. The minimal and maximal total number and area of myelinated axons varied from 17,000 to 21,000 and from 8.95 to 14.02 microm(2), respectively. There was a significant increase in the myelin thickness of axons with age. Connective tissue gradually increased in later decades and was more pronounced in the eighth decade. The present study provides novel baseline morphometric data on the ON that would be of help to future studies.
Collapse
|
26
|
Barnett CP, Mendoza-Londono R, Blaser S, Gillis J, Dupuis L, Levin AV, Chiang PW, Spector E, Reardon W. Aplasia of cochlear nerves and olfactory bulbs in association with SOX10 mutation. Am J Med Genet A 2009; 149A:431-6. [PMID: 19208381 DOI: 10.1002/ajmg.a.32657] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A 17-month-old boy was referred with profound sensorineural hearing loss (SNHL), severe visual impairment and developmental delay. Neuroimaging identified hypomyelination and cochlear nerve aplasia. He was noted to have fair skin and hair and multiple areas of cutaneous hyperpigmentation. Previous investigations including karyotype, array comparative genomic hybridization (aCGH) and a full metabolic screen were normal. A novel missense mutation of the highly conserved high mobility group (HMG) domain of SOX10 was identified (Q174P:c.521A>C). This case represents the first description of aplasia of the cochlear nerve due to a SOX10 mutation.
Collapse
Affiliation(s)
- C P Barnett
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Sharma V, Nag TC, Wadhwa S, Roy TS. Stereological investigation and expression of calcium-binding proteins in developing human inferior colliculus. J Chem Neuroanat 2008; 37:78-86. [PMID: 19095058 DOI: 10.1016/j.jchemneu.2008.11.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2008] [Revised: 09/24/2008] [Accepted: 11/07/2008] [Indexed: 10/21/2022]
Abstract
The mammalian inferior colliculus (IC) is a major relay nucleus in the auditory pathway. Prenatal development of the human IC has been inadequately studied. The present study reports the morphometric development and maturation of the human IC using unbiased stereology, in 18 aborted fetuses of various gestational ages (12-29 weeks) and two babies aged 40 postnatal days (PND) and 5 months (that died of postoperative complications). It also demonstrates the functional maturation of the IC by examining the expression of calcium-binding proteins--parvalbumin (PV) and calbindin (CB). There was a significant increase in the total number of neurons and glia from 18 weeks of gestation (WG). The glia and neuron volume increased significantly from 16 WG to 22 WG, respectively. The total volume of IC also increased significantly from 18 WG onwards. On the other hand, the number and volume of undifferentiated cell bodies across all ages decreased significantly. Expression of CB was concentrated in the dorsal cortex while that of PV was mainly confined to the central nucleus of the IC, possibly indicating an early segregation of parallel processing of information in the auditory pathways. Intense staining for CB in the soma and dendrites appeared earlier than that of the PV. The morphological maturation appeared to overlap the onset of functional maturation suggesting an activity-dependent mechanism in the development of IC.
Collapse
Affiliation(s)
- Vikram Sharma
- Department of Anatomy, All India Institute of Medical Sciences, New Delhi 110029, India
| | | | | | | |
Collapse
|
28
|
Jardri R, Pins D, Houfflin-Debarge V, Chaffiotte C, Rocourt N, Pruvo JP, Steinling M, Delion P, Thomas P. Fetal cortical activation to sound at 33 weeks of gestation: a functional MRI study. Neuroimage 2008; 42:10-8. [PMID: 18539048 DOI: 10.1016/j.neuroimage.2008.04.247] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 04/17/2008] [Accepted: 04/25/2008] [Indexed: 10/22/2022] Open
Abstract
Hearing already functions before birth, but little is known about the neural basis of fetal life experiences. Recent imaging studies have validated the use of functional magnetic resonance imaging (fMRI) in pregnant women at 38-weeks of gestation. The aim of the present study was to examine fetal brain activation to sound, using fMRI at the beginning of the third trimester of pregnancy. 6 pregnant women between 28- and 34-weeks of gestation were scanned using a magnetic strength of 1.5 T, with an auditory stimulus applied to their abdomen. 3 fetuses with a gestational age of 33 weeks, showed significant activation to sound in the left temporal lobe, measured using a new data-driven approach (Independent Component Analysis for fMRI time series). Only 2 of these fetuses showed left temporal activation, when the standard voxel-wise analysis method was used (p=0.007; p=0.001). Moreover, motion parameters added as predictors of the General Linear Model confirmed that motion cannot account for the signal variance in the fetal temporal cortex (p=0.01). Comparison between the statistical maps obtained from MRI scans of the fetuses with those obtained from adults, made it possible to confirm our hypothesis, that there is brain activation in the primary auditory cortex in response to sound. Measurement of the fetal hemodynamic response revealed an average fMRI signal change of +3.5%. This study shows that it is possible to use fMRI to detect early fetal brain function, but also confirms that sound processing occurs beyond the reflexive sub-cortical level, at the beginning of the third trimester of pregnancy.
Collapse
Affiliation(s)
- Renaud Jardri
- Laboratoire de Neurosciences Fonctionnelles et Pathologies, CNRS UMR 8160, Université Lille 2, CHRU de Lille, France.
| | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Minagawa-Kawai Y, Mori K, Hebden JC, Dupoux E. Optical imaging of infants' neurocognitive development: Recent advances and perspectives. Dev Neurobiol 2008; 68:712-28. [DOI: 10.1002/dneu.20618] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
30
|
Montie EW, Schneider GE, Ketten DR, Marino L, Touhey KE, Hahn ME. Neuroanatomy of the Subadult and Fetal Brain of the Atlantic White-sided Dolphin (Lagenorhynchus acutus) from in Situ Magnetic Resonance Images. Anat Rec (Hoboken) 2007; 290:1459-79. [DOI: 10.1002/ar.20612] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|