1
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Meng J, Mao F. On the earliest evolution of the mammaliaform teeth, jaw joint and middle ear. Clin Transl Med 2024; 14:e1768. [PMID: 39031974 PMCID: PMC11259600 DOI: 10.1002/ctm2.1768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2024] [Accepted: 07/08/2024] [Indexed: 07/22/2024] Open
Affiliation(s)
- Jin Meng
- Division of PaleontologyAmerican Museum of Natural HistoryNew York CityNew YorkUSA
- Earth and Environmental SciencesGraduate CenterCity University of New YorkNew York CityNew YorkUSA
| | - Fangyuan Mao
- Key Laboratory of Vertebrate Evolution and Human OriginsInstitute of Vertebrate Paleontology and PaleoanthropologyChinese Academy of SciencesBeijingChina
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2
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She Y, Ren R, Jiang N. Mechanical stress can regulate temporomandibular joint cavitation via signalling pathways. Dev Biol 2024; 507:1-8. [PMID: 38114053 DOI: 10.1016/j.ydbio.2023.12.006] [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: 05/04/2023] [Revised: 12/10/2023] [Accepted: 12/15/2023] [Indexed: 12/21/2023]
Abstract
The temporomandibular joint (TMJ), composed of temporal fossa, mandibular condyle and a fibrocartilage disc with upper and lower cavities, is the biggest synovial joint and biomechanical hinge of the craniomaxillofacial musculoskeletal system. The initial events that give rise to TMJ cavities across diverse species are not fully understood. Most studies focus on the pivotal role of molecules such as Indian hedgehog (Ihh) and hyaluronic acid (HA) in TMJ cavitation. Although biologists have observed that mechanical stress plays an irreplaceable role in the development of biological tissues and organs, few studies have been concerned with how mechanical stress regulates TMJ cavitation. Based on the evidence from human or other animal embryos today, it is implicated that mechanical stress plays an essential role in TMJ cavitation. In this review, we discuss the relationship between mechanical stress and TMJ cavitation from evo-devo perspectives and review the clinical features and potential pathogenesis of TMJ dysplasia.
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Affiliation(s)
- Yilin She
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Disease and West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Rong Ren
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Disease and West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Nan Jiang
- State Key Laboratory of Oral Diseases and National Clinical Research Center for Oral Disease and West China Hospital of Stomatology, Sichuan University, Chengdu, China.
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3
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Fernández-Rubio EM, Radlanski RJ. Development of the human primary and secondary jaw joints. Ann Anat 2024; 251:152169. [PMID: 37875166 DOI: 10.1016/j.aanat.2023.152169] [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: 06/27/2023] [Revised: 09/26/2023] [Accepted: 10/09/2023] [Indexed: 10/26/2023]
Abstract
This study investigates the development of the primary and secondary jaw joints in humans, focusing on their concomitance and subsequent disconnection. Development begins with the primary temporomandibular joint as a connection between Meckel's cartilage and the incus, while the secondary temporomandibular joint develops anteriorly as an articulation between the mandibular condyle and the mandibular fossa. Previous research in mice has provided insights into the morphogenesis of these joints, but their specific development of the 3D morphogenesis in humans remains unclear. To address this gap, histological serial sections of embryos and fetuses ranging from 19 to 230 mm crown-rump length were analyzed. The 3D morphogenesis of the middle ear and the temporomandibular joint was examined, paying attention to the morphological characteristics, timing, and potential mechanisms of movement and disconnection. The primary jaw joint is initially formed at 25 mm (8th week), followed by the appearance of the secondary jaw joint arising at 87 mm (12th week). Both joints persist present simultaneously, until a separation occurs between 150 and 230 mm (18th-24th week). It is remarkable that both joints remain concomitant and function somehow for a period exceeding 6 weeks, with the mechanism of their separation still unclear. Understanding the precise timing and functional movements involved with these temporarily connected joints is crucial for comprehending the overall development of the temporomandibular joint. Further research is needed to explore the molecular and cellular processes underlying these developmental changes.
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Affiliation(s)
- E M Fernández-Rubio
- Charité - Campus Benjamin Franklin at Freie Universität Berlin Center for Dental and Craniofacial Sciences Dept. of Craniofacial Developmental Biology, Assmannshauser Str. 4-6, Berlin 14197, Germany
| | - R J Radlanski
- Charité - Campus Benjamin Franklin at Freie Universität Berlin Center for Dental and Craniofacial Sciences Dept. of Craniofacial Developmental Biology, Assmannshauser Str. 4-6, Berlin 14197, Germany.
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4
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Wang H, Wang Y. Middle ear innovation in Early Cretaceous eutherian mammals. Nat Commun 2023; 14:6831. [PMID: 37884521 PMCID: PMC10603157 DOI: 10.1038/s41467-023-42606-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 10/16/2023] [Indexed: 10/28/2023] Open
Abstract
The middle ear ossicles in modern mammals are repurposed from postdentary bones in non-mammalian cynodonts. Recent discoveries by palaeontological and embryonic studies have developed different models for the middle ear evolution in mammaliaforms. However, little is known about the evolutionary scenario of the middle ear in early therians. Here we report a detached middle ear preserved in a new eutherian mammal from the Early Cretaceous Jehol Biota. The well-preserved articulation of the malleus and incus suggest that the saddle-shaped incudomallear joint is a major apomorphy of Early Cretaceous eutherians. By contrast to the distinct saddle-like incudomallear articulation in therians, differences between the overlapping versus the half-overlapping incudomallear joints in monotremes and stem mammals would be relatively minor. The middle ear belongs to the microtype by definition, indicating its adaptation to high-frequency hearing. Current evidence indicates that significant evolutionary innovations of the middle ear in modern therians evolved in Early Cretaceous.
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Affiliation(s)
- Haibing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 100044, Beijing, China.
| | - Yuanqing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, 100044, Beijing, China.
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, 100049, Beijing, China.
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5
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Anthwal N, Tucker AS. Evolution and development of the mammalian jaw joint: Making a novel structure. Evol Dev 2023; 25:3-14. [PMID: 36504442 PMCID: PMC10078425 DOI: 10.1111/ede.12426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Revised: 11/08/2022] [Accepted: 11/22/2022] [Indexed: 12/14/2022]
Abstract
A jaw joint between the squamosal and dentary is a defining feature of mammals and is referred to as the temporomandibular joint (TMJ) in humans. Driven by changes in dentition and jaw musculature, this new joint evolved early in the mammalian ancestral lineage and permitted the transference of the ancestral jaw joint into the middle ear. The fossil record demonstrates the steps in the cynodont lineage that led to the acquisition of the TMJ, including the expansion of the dentary bone, formation of the coronoid process, and initial contact between the dentary and squamosal. From a developmental perspective, the components of the TMJ form through tissue interactions of muscle and skeletal elements, as well as through interaction between the jaw and the cranial base, with the signals involved in these interactions being both biomechanical and biochemical. In this review, we discuss the development of the TMJ in an evolutionary context. We describe the evolution of the TMJ in the fossil record and the development of the TMJ in embryonic development. We address the formation of key elements of the TMJ and how knowledge from developmental biology can inform our understanding of TMJ evolution.
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Affiliation(s)
- Neal Anthwal
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentisry, Oral and Craniofacial Sciences, London, UK
| | - Abigail S Tucker
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentisry, Oral and Craniofacial Sciences, London, UK
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6
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Wang HB, Hoffmann S, Wang DC, Wang YQ. A new mammal from the Lower Cretaceous Jehol Biota and implications for eutherian evolution. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210042. [PMID: 35125007 PMCID: PMC8819371 DOI: 10.1098/rstb.2021.0042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Here we report on a new Early Cretaceous eutherian represented by a partial skeleton from the Jiufotang Formation at Sihedang site, Lingyuan City, Liaoning Province that fills a crucial gap between the earliest eutherians from the Yixian Formation and later Cretaceous eutherians. The new specimen reveals, to our knowledge for the first time in eutherians, that the Meckelian cartilage was ossified but reduced in size, confirming a complete detachment of the middle ear from the lower jaw. Seven hyoid elements, including paired stylohyals, epihyals and thyrohyals and the single basihyal are preserved. For the inner ear the ossified primary lamina, base of the secondary lamina, ossified cochlear ganglion and secondary crus commune are present and the cochlear canal is coiled through 360°. In addition, plesiomorphic features of the dentition include weak conules, lack of pre- and post-cingula and less expanded protocones on the upper molars and height differential between the trigonid and talonid, a large protoconid and a small paraconid on the lower molars. The new taxon displays an alternating pattern of tooth replacement with P3 being the last upper premolar to erupt similar to the basal eutherian Juramaia. Parsimony analysis places the new taxon with Montanalestes, Sinodelphys and Ambolestes as a sister group to other eutherians. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.
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Affiliation(s)
- Hai-Bing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, People's Republic of China.,Centre for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, People's Republic of China.,Key State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, People's Republic of China
| | - Simone Hoffmann
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY, USA
| | - Dian-Can Wang
- Department of Oral and Maxillofacial Surgery, Peking University School of Stomatology, 22 South Zhongguancun Avenue, Beijing, People's Republic of China
| | - Yuan-Qing Wang
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, People's Republic of China.,Centre for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Beijing, People's Republic of China.,College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, People's Republic of China
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7
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Conith AJ, Meagher MA, Dumont ER. The influence of divergent reproductive strategies in shaping modularity and morphological evolution in mammalian jaws. J Evol Biol 2021; 35:164-179. [PMID: 34624153 DOI: 10.1111/jeb.13944] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 08/16/2021] [Accepted: 09/23/2021] [Indexed: 01/17/2023]
Abstract
Marsupial neonates are born at an earlier developmental stage than placental mammals, but the rapid development of their forelimbs and cranial skeleton allows them to climb to the pouch, begin suckling and complete their development ex utero. The mechanical environment in which marsupial neonates develop is vastly different from that of placental neonates, which exhibit a more protracted development of oral muscles and bones. This difference in reproductive strategy has been theorized to constrain morphological evolution in the oral region of marsupials. Here, we use 3D morphometrics to characterize one of these oral bones, the lower jaw (dentary), and assess modularity (pattern of covariation among traits), morphological disparity and rates of morphological evolution in two clades of carnivorous mammals: the marsupial Dasyuromorphia and placental fissiped Carnivora. We find that dasyuromorph dentaries have fewer modules than carnivorans and exhibit tight covariation between the angular and coronoid processes, the primary attachment sites for jaw-closing muscles. This pattern of modularity may result from the uniform action of muscles on the developing mandible during suckling. Carnivorans are free from this constraint and exhibit a pattern of modularity that more strongly reflects genetic and developmental signals of trait covariation. Alongside differences in modularity, carnivorans exhibit greater disparity and faster rates of morphological evolution compared with dasyuromorphs. Taken together, this suggests dasyuromorphs have retained a signal of trait covariation that reflects the outsized influence of muscular force during early development, a feature that may have impacted the ability of marsupial carnivores to explore specialized regions of morphospace.
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Affiliation(s)
- Andrew J Conith
- Biology Department, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Molly A Meagher
- Natural Resources Conservation, University of Massachusetts, Amherst, Massachusetts, USA
| | - Elizabeth R Dumont
- Department of Life and Environmental Sciences, University of California, Merced, California, USA
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8
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Thiha P, Higashihori N, Kano S, Moriyama K. Histone methyltransferase SET domain bifurcated 1 negatively regulates parathyroid hormone/parathyroid hormone-related peptide receptor to control chondrocyte proliferation in Meckel's cartilage. Arch Oral Biol 2021; 131:105251. [PMID: 34521010 DOI: 10.1016/j.archoralbio.2021.105251] [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] [Received: 03/25/2021] [Revised: 07/15/2021] [Accepted: 08/27/2021] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The aim of this study is to show that the proliferation of chondrocytes is regulated by SET domain bifurcated 1 (SETDB1) along with the downregulation of parathyroid hormone (PTH)/parathyroid hormone-related peptide (PTHrP) receptor in Meckel's cartilage. DESIGN Setdb1 was knocked down or overexpressed in a mouse chondrogenic ATDC5 cells, by transfecting the cells with short interfering RNA against Setdb1 or wild-type Setdb1 expression vector, respectively. Cell proliferation was detected by bromodeoxyuridine incorporation. Setdb1 was conditionally deleted in neural crest cells with Wnt1-Cre (Setdb1 conditional knockout mice). Immunofluorescence staining of paraffin sections of embryonic days 13.5 and 14.5 Setdb1 conditional knockout mice or transfected ATDC5 cells was performed to detect PTH/PTHrP receptor. Protein kinase B (AKT) phosphorylation inhibitor was added to both siRNA-transfected ATDC5 cultures to determine whether AKT activation induces PTH/PTHrP receptor expression after Setdb1 knockdown or vice versa. RESULTS Setdb1 knockdown in ATDC5 cells showed increased cell proliferation and parathyroid hormone receptor 1 expression. Contrasting results were observed in the Setdb1-overexpressed wild-type cells. Immunofluorescence staining showed the highly expressed PTH/PTHrP receptor in Setdb1-knocked down ATDC5 cells and in the chondrocytes of Setdb1 conditional knockout embryonic Meckel's cartilage, indicating the negative regulation of SETDB1 on PTH/PTHrP receptor. Strong staining of phosphorylated AKT was observed in Setdb1-knocked down ATDC5 cells. However, the inhibition of AKT phosphorylation significantly reduced both the PTH/PTHrP receptor staining and the Setdb1-knockdown-induced increase in ATDC5 cell proliferation. CONCLUSIONS Our findings contribute new insights on SETDB1 function in relation with AKT and PTH/PTHrP receptor during chondrocyte proliferation.
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Affiliation(s)
- Phyo Thiha
- Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Norihisa Higashihori
- Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan.
| | - Sakurako Kano
- Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Keiji Moriyama
- Maxillofacial Orthognathics, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
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9
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Cook LE, Newton AH, Hipsley CA, Pask AJ. Postnatal development in a marsupial model, the fat-tailed dunnart (Sminthopsis crassicaudata; Dasyuromorphia: Dasyuridae). Commun Biol 2021; 4:1028. [PMID: 34475507 PMCID: PMC8413461 DOI: 10.1038/s42003-021-02506-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Accepted: 07/29/2021] [Indexed: 02/07/2023] Open
Abstract
Marsupials exhibit unique biological features that provide fascinating insights into many aspects of mammalian development. These include their distinctive mode of reproduction, altricial stage at birth, and the associated heterochrony that is required for their crawl to the pouch and teat attachment. Marsupials are also an invaluable resource for mammalian comparative biology, forming a distinct lineage from the extant placental and egg-laying monotreme mammals. Despite their unique biology, marsupial resources are lagging behind those available for placentals. The fat-tailed dunnart (Sminthopsis crassicaudata) is a laboratory based marsupial model, with simple and robust husbandry requirements and a short reproductive cycle making it amenable to experimental manipulations. Here we present a detailed staging series for the fat-tailed dunnart, focusing on their accelerated development of the forelimbs and jaws. This study provides the first skeletal developmental series on S. crassicaudata and provides a fundamental resource for future studies exploring mammalian diversification, development and evolution.
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Affiliation(s)
- Laura E Cook
- School of Biosciences, University of Melbourne, Parkville, VIC, Australia
| | - Axel H Newton
- Department of Anatomy and Developmental Biology, Monash University, Clayton, VIC, Australia
| | - Christy A Hipsley
- School of Biosciences, University of Melbourne, Parkville, VIC, Australia
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
- Department of Sciences, Museums Victoria, Carlton, VIC, Australia
| | - Andrew J Pask
- School of Biosciences, University of Melbourne, Parkville, VIC, Australia.
- Department of Sciences, Museums Victoria, Carlton, VIC, Australia.
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10
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Howenstine AO, Sadier A, Anthwal N, Lau CL, Sears KE. Non-model systems in mammalian forelimb evo-devo. Curr Opin Genet Dev 2021; 69:65-71. [PMID: 33684847 PMCID: PMC8364859 DOI: 10.1016/j.gde.2021.01.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 01/09/2023]
Abstract
Mammal forelimbs are highly diverse, ranging from the elongated wing of a bat to the stout limb of the mole. The mammal forelimb has been a long-standing system for the study of early developmental patterning, proportional variation, shape change, and the reduction of elements. However, most of this work has been performed in mice, which neglects the wide variation present across mammal forelimbs. This review emphasizes the critical role of non-model systems in limb evo-devo and highlights new emerging models and their potential. We discuss the role of gene networks in limb evolution, and touch on functional analyses that lay the groundwork for further developmental studies. Mammal limb evo-devo is a rich field, and here we aim to synthesize the findings of key recent works and the questions to which they lead.
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Affiliation(s)
- Aidan O Howenstine
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA, 90095, United States
| | - Alexa Sadier
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA, 90095, United States
| | - Neal Anthwal
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA, 90095, United States; Centre for Craniofacial and Regenerative Biology, King's CollegeLondon, 27th Floor Guy's Tower, London, SE1 9RT, UK
| | - Clive Lf Lau
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA, 90095, United States
| | - Karen E Sears
- Department of Ecology and Evolutionary Biology, University of California at Los Angeles, Los Angeles, CA, 90095, United States.
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11
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Wang J, Wible JR, Guo B, Shelley SL, Hu H, Bi S. A monotreme-like auditory apparatus in a Middle Jurassic haramiyidan. Nature 2021; 590:279-283. [PMID: 33505017 DOI: 10.1038/s41586-020-03137-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 12/10/2020] [Indexed: 01/30/2023]
Abstract
Among extant vertebrates, mammals are distinguished by having a chain of three auditory ossicles (the malleus, incus and stapes) that transduce sound waves and promote an increased range of audible-especially high-frequencies1. By contrast, the homologous bones in early fossil mammals and relatives also functioned in chewing through their bony attachments to the lower jaw2. Recent discoveries of well-preserved Mesozoic mammals have provided glimpses into the transition from the dual (masticatory and auditory) to the single auditory function for the ossicles, which is now widely accepted to have occurred at least three times in mammal evolution3-6. Here we report a skull and postcranium that we refer to the haramiyidan Vilevolodon diplomylos (dating to the Middle Jurassic epoch (160 million years ago)) and that shows excellent preservation of the malleus, incus and ectotympanic (which supports the tympanic membrane). After comparing this fossil with other Mesozoic and extant mammals, we propose that the overlapping incudomallear articulation found in this and other Mesozoic fossils, in extant monotremes and in early ontogeny in extant marsupials and placentals is a morphology that evolved in several groups of mammals in the transition from the dual to the single function for the ossicles.
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Affiliation(s)
- Junyou Wang
- Centre for Vertebrate Evolutionary Biology, Institute of Palaeontology, Yunnan University, Kunming, China.,Inner Mongolia Museum of Natural History, Hohhot, China
| | - John R Wible
- Centre for Vertebrate Evolutionary Biology, Institute of Palaeontology, Yunnan University, Kunming, China. .,Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA.
| | - Bin Guo
- Inner Mongolia Museum of Natural History, Hohhot, China
| | - Sarah L Shelley
- Section of Mammals, Carnegie Museum of Natural History, Pittsburgh, PA, USA.,School of Geosciences, University of Edinburgh, Edinburgh, UK
| | - Han Hu
- Zoology Division, School of Environmental and Rural Sciences, University of New England, Armidale, New South Wales, Australia
| | - Shundong Bi
- Centre for Vertebrate Evolutionary Biology, Institute of Palaeontology, Yunnan University, Kunming, China. .,Department of Biology, Indiana University of Pennsylvania, Indiana, PA, USA.
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12
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Mozaffari M, Nash R, Tucker AS. Anatomy and Development of the Mammalian External Auditory Canal: Implications for Understanding Canal Disease and Deformity. Front Cell Dev Biol 2021; 8:617354. [PMID: 33553153 PMCID: PMC7857502 DOI: 10.3389/fcell.2020.617354] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 12/11/2020] [Indexed: 12/15/2022] Open
Abstract
The mammalian ear is made up of three parts (the outer, middle, and inner ear), which work together to transmit sound waves into neuronal signals perceived by our auditory cortex as sound. This review focuses on the often-neglected outer ear, specifically the external auditory meatus (EAM), or ear canal. Within our complex hearing pathway, the ear canal is responsible for funneling sound waves toward the tympanic membrane (ear drum) and into the middle ear, and as such is a physical link between the tympanic membrane and the outside world. Unique anatomical adaptations, such as its migrating epithelium and cerumen glands, equip the ear canal for its function as both a conduit and a cul-de-sac. Defects in development, or later blockages in the canal, lead to congenital or acquired conductive hearing loss. Recent studies have built on decades-old knowledge of ear canal development and suggest a novel multi-stage, complex and integrated system of development, helping to explain the mechanisms underlying congenital canal atresia and stenosis. Here we review our current understanding of ear canal development; how this biological lumen is made; what determines its location; and how its structure is maintained throughout life. Together this knowledge allows clinical questions to be approached from a developmental biology perspective.
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Affiliation(s)
- Mona Mozaffari
- Centre for Craniofacial and Regenerative Biology, King's College London, Guy's Hospital, London, United Kingdom
| | - Robert Nash
- Department of Paediatric Otolaryngology, Cochlear Implants, Great Ormond Street Hospital for Children NHS Trust, London, United Kingdom
| | - Abigail S Tucker
- Centre for Craniofacial and Regenerative Biology, King's College London, Guy's Hospital, London, United Kingdom
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13
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Ankamreddy H, Bok J, Groves AK. Uncovering the secreted signals and transcription factors regulating the development of mammalian middle ear ossicles. Dev Dyn 2020; 249:1410-1424. [PMID: 33058336 DOI: 10.1002/dvdy.260] [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: 08/12/2020] [Revised: 10/11/2020] [Accepted: 10/11/2020] [Indexed: 12/22/2022] Open
Abstract
The mammalian middle ear comprises a chain of ossicles, the malleus, incus, and stapes that act as an impedance matching device during the transmission of sound from the tympanic membrane to the inner ear. These ossicles are derived from cranial neural crest cells that undergo endochondral ossification and subsequently differentiate into their final functional forms. Defects that occur during middle ear development can result in conductive hearing loss. In this review, we summarize studies describing the crucial roles played by signaling molecules such as sonic hedgehog, bone morphogenetic proteins, fibroblast growth factors, notch ligands, and chemokines during the differentiation of neural crest into the middle ear ossicles. In addition to these cell-extrinsic signals, we also discuss studies on the function of transcription factor genes such as Foxi3, Tbx1, Bapx1, Pou3f4, and Gsc in regulating the development and morphology of the middle ear ossicles.
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Affiliation(s)
| | - Jinwoong Bok
- Department of Anatomy, Yonsei University College of Medicine, Seoul, South Korea.,Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, South Korea
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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14
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Svandova E, Anthwal N, Tucker AS, Matalova E. Diverse Fate of an Enigmatic Structure: 200 Years of Meckel's Cartilage. Front Cell Dev Biol 2020; 8:821. [PMID: 32984323 PMCID: PMC7484903 DOI: 10.3389/fcell.2020.00821] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/03/2020] [Indexed: 12/16/2022] Open
Abstract
Meckel's cartilage was first described by the German anatomist Johann Friedrich Meckel the Younger in 1820 from his analysis of human embryos. Two hundred years after its discovery this paper follows the development and largely transient nature of the mammalian Meckel's cartilage, and its role in jaw development. Meckel's cartilage acts as a jaw support during early development, and a template for the later forming jaw bones. In mammals, its anterior domain links the two arms of the dentary together at the symphysis while the posterior domain ossifies to form two of the three ear ossicles of the middle ear. In between, Meckel's cartilage transforms to a ligament or disappears, subsumed by the growing dentary bone. Several human syndromes have been linked, directly or indirectly, to abnormal Meckel's cartilage formation. Herein, the evolution, development and fate of the cartilage and its impact on jaw development is mapped. The review focuses on developmental and cellular processes that shed light on the mechanisms behind the different fates of this cartilage, examining the control of Meckel's cartilage patterning, initiation and maturation. Importantly, human disorders and mouse models with disrupted Meckel's cartilage development are highlighted, in order to understand how changes in this cartilage impact on later development of the dentary and the craniofacial complex as a whole. Finally, the relative roles of tissue interactions, apoptosis, autophagy, macrophages and clast cells in the removal process are discussed. Meckel's cartilage is a unique and enigmatic structure, the development and function of which is starting to be understood but many interesting questions still remain.
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Affiliation(s)
- Eva Svandova
- Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
| | - Neal Anthwal
- Centre for Craniofacial and Regenerative Biology, King’s College London, Guy’s Hospital, London, United Kingdom
| | - Abigail S. Tucker
- Centre for Craniofacial and Regenerative Biology, King’s College London, Guy’s Hospital, London, United Kingdom
| | - Eva Matalova
- Institute of Animal Physiology and Genetics, Academy of Sciences, Brno, Czechia
- Department of Physiology, University of Veterinary and Pharmaceutical Sciences, Brno, Czechia
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