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Abstract
Congenital heart disease is the most frequent birth defect and the leading cause of death for the fetus and in the first year of life. The wide phenotypic diversity of congenital heart defects requires expert diagnosis and sophisticated repair surgery. Although these defects have been described since the seventeenth century, it was only in 2005 that a consensus international nomenclature was adopted, followed by an international classification in 2017 to help provide better management of patients. Advances in genetic engineering, imaging, and omics analyses have uncovered mechanisms of heart formation and malformation in animal models, but approximately 80% of congenital heart defects have an unknown genetic origin. Here, we summarize current knowledge of congenital structural heart defects, intertwining clinical and fundamental research perspectives, with the aim to foster interdisciplinary collaborations at the cutting edge of each field. We also discuss remaining challenges in better understanding congenital heart defects and providing benefits to patients.
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Affiliation(s)
- Lucile Houyel
- Unité de Cardiologie Pédiatrique et Congénitale and Centre de Référence des Malformations Cardiaques Congénitales Complexes (M3C), Hôpital Necker-Enfants Malades, Assistance Publique-Hôpitaux de Paris (AP-HP), 75015 Paris, France.,Université de Paris, 75015 Paris, France
| | - Sigolène M Meilhac
- Université de Paris, 75015 Paris, France.,Imagine-Institut Pasteur Unit of Heart Morphogenesis, INSERM UMR 1163, 75015 Paris, France;
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2
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Naqvi N, McCarthy KP, Ho SY. Anatomy of the atrial septum and interatrial communications. J Thorac Dis 2018; 10:S2837-S2847. [PMID: 30305943 DOI: 10.21037/jtd.2018.02.18] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Deficiencies in the septum separating the two atrial chambers are among the most common of congenital heart malformations. This article reviews the developmental aspects of the partitioning of the primitive atrium into right and left atrial chambers, the anatomical components of the atrial septum, and deficiencies that produce the various types of interatrial communications. Knowledge of the components of the true atrial septum in the developed heart clarifies the morphology of various types of interatrial communications. The oval fossa defect (also termed secundum ASD) is located within the true septum. The patent foramen ovale (PFO) is a tunnel-like passageway between the free edge of the overlapping ovale fossa valve and its muscular rim. Other defects such as superior and inferior sinus venosus defects, coronary sinus defects, and ostium primum defects lie outside the area of the true septum.
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Affiliation(s)
- Nitha Naqvi
- Paediatric Cardiology, Royal Brompton Hospital, Imperial College London, London, UK
| | - Karen P McCarthy
- Cardiac Morphology, Royal Brompton Hospital, Imperial College London, London, UK
| | - Siew Yen Ho
- Cardiac Morphology, Royal Brompton Hospital, Imperial College London, London, UK
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3
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Elliott GC, Gurtu R, McCollum C, Newman WG, Wang T. Foramen ovale closure is a process of endothelial-to-mesenchymal transition leading to fibrosis. PLoS One 2014; 9:e107175. [PMID: 25215881 PMCID: PMC4162597 DOI: 10.1371/journal.pone.0107175] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/08/2014] [Indexed: 11/18/2022] Open
Abstract
Patent foramen ovale (PFO) is an atrial septal deformity present in around 25% of the general population. PFO is associated with major causes of morbidity, including stroke and migraine. PFO appears to be heritable but genes involved in the closure of foramen ovale have not been identified. The aim of this study is to determine molecular pathways and genes that are responsible to the postnatal closure of the foramen ovale. Using Sprague-Dawley rat hearts as a model we analysed the dynamic histological changes and gene expressions at the foramen ovale region between embryonic day 20 and postnatal day 7. We observed a gradual loss of the endothelial marker PECAM1, an upregulation of the mesenchymal marker vimentin and α-smooth muscle actin, the elevation of the transcription factor Snail, and an increase of fibroblast activation protein (FAP) in the foramen ovale region as well as the deposition of collagen-rich connective tissues at the closed foramen ovale, suggesting endothelial-to-mesenchymal transition (EndMT) occurring during foramen ovale closure which leads to fibrosis. In addition, Notch1 and Notch3 receptors, Notch ligand Jagged1 and Notch effector HRT1 were highly expressed in the endocardium of the foramen ovale region during EndMT. Activation of Notch3 alone in an endothelial cell culture model was able to drive EndMT and transform endothelial cells to mesenchymal phenotype. Our data demonstrate for the first time that FO closure is a process of EndMT-mediated fibrosis, and Notch signalling is an important player participating in this process. Elucidation of the molecular mechanisms of the closure of foramen ovale informs the pathogenesis of PFO and may provide potential options for screening and prevention of PFO related conditions.
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Affiliation(s)
- Graeme C. Elliott
- Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
| | - Rockesh Gurtu
- Academic Surgery Unit, Education and Research Centre, University Hospital of South Manchester, Manchester, United Kingdom
| | - Charles McCollum
- Academic Surgery Unit, Education and Research Centre, University Hospital of South Manchester, Manchester, United Kingdom
| | - William G. Newman
- Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
- Centre for Genomic Medicine, Central Manchester University Hospitals NHS Foundation Trust, Manchester, United Kingdom
| | - Tao Wang
- Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom
- * E-mail:
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4
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Abstract
The development of the embryonic heart is dependent upon the generation and incorporation of different mesenchymal subpopulations that derive from intra- and extra-cardiac sources, including the endocardium, epicardium, neural crest, and second heart field. Each of these populations plays a crucial role in cardiovascular development, in particular in the formation of the valvuloseptal apparatus. Notwithstanding shared mechanisms by which these cells are generated, their fate and function differ profoundly by their originating source. While most of our early insights into the origin and fate of the cardiac mesenchyme has come from experimental studies in avian model systems, recent advances in transgenic mouse technology has enhanced our ability to study these cell populations in the mammalian heart. In this article, we will review the current understanding of the role of cardiac mesenchyme in cardiac morphogenesis and discuss several new paradigms based on recent studies in the mouse.
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Affiliation(s)
- Brian S Snarr
- Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, South Carolina 29425, USA
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5
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Mommersteeg MTM, Soufan AT, de Lange FJ, van den Hoff MJB, Anderson RH, Christoffels VM, Moorman AFM. Two Distinct Pools of Mesenchyme Contribute to the Development of the Atrial Septum. Circ Res 2006; 99:351-3. [PMID: 16873717 DOI: 10.1161/01.res.0000238360.33284.a0] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Closure of the primary atrial foramen is achieved by fusion of the atrioventricular cushions with the mesenchymal cap on the leading edge of the muscular primary atrial septum. A fourth component involved is the vestibular spine, originally described by His in 1880 as an intra-cardiac continuation of the extra-cardiac mesenchyme of the dorsal mesocardium. The morphogenesis of this area is of great clinical interest, because of the high incidence of atrial and atrioventricular septal defects. Nonetheless, the origin of the participating components is largely unknown. Here we report that the primary atrial foramen is surrounded in its entirety by mesenchyme derived from endocardium. A second population of mesenchyme not derived from endocardium was observed at the caudal margin of the mesenchymal atrial cap, entirely embedded within the mesenchyme derived from endocardium and contiguous with the mesenchyme of the dorsal mesocardium. Our reconstructions show this second population does indeed take the form of a short spine, albeit that it is the right pulmonary ridge, rather than this spine, that protrudes into the atrial lumen. From the stance of morphological description, therefore, there is little thus far to substantiate the existence of an atrial spine.
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Affiliation(s)
- Mathilda T M Mommersteeg
- Molecular and Experimental Cardiology Group, Academic Medical Centre, University of Amsterdam, The Netherlands
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6
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Wang Q, Lan Y, Cho ES, Maltby KM, Jiang R. Odd-skipped related 1 (Odd 1) is an essential regulator of heart and urogenital development. Dev Biol 2005; 288:582-94. [PMID: 16223478 PMCID: PMC3869089 DOI: 10.1016/j.ydbio.2005.09.024] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2005] [Revised: 09/07/2005] [Accepted: 09/13/2005] [Indexed: 10/25/2022]
Abstract
The Odd-skipped related 1 (Odd 1) gene encodes a zinc finger protein homologous to the Drosophila Odd-skipped class transcription factors that play critical roles in embryonic patterning and tissue morphogenesis. We have generated mice carrying a targeted null mutation in the Odd 1 gene and show that Odd 1 is essential for heart and intermediate mesoderm development. Odd 1(-/-) mutant mouse embryos fail to form atrial septum, display dilated atria with hypoplastic venous valves, and exhibit blood backflow from the heart into systemic veins. In contrast to other transcription factors implicated in atrial septum development, Odd 1 mRNA expression is restricted to the central dorsal domain of the atrial myocardium during normal heart development. Moreover, expression patterns of known key regulatory genes of atrial septum development, including Nkx2.5, Pitx2, and Tbx5, are unaltered in the developing heart in Odd 1(-/-) mutants compared to that of the wild-type littermates. Furthermore, homozygous Odd 1(-/-) mutant embryos exhibit complete agenesis of adrenal glands, metanephric kidneys, gonads, and defects in pericardium formation. Detailed molecular marker analyses show that key regulators of early intermediate mesoderm development, including Lhx1, Pax2, and Wt1, are all down-regulated and nephrogenic mesenchyme undergoes massive apoptosis, resulting in disruption of nephric duct elongation and failure of metanephric induction in the Odd 1(-/-) mutant embryos. These data provide new insights into the molecular mechanisms underlying heart morphogenesis and urogenital development.
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Affiliation(s)
- Qingru Wang
- Center for Oral Biology and Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Yu Lan
- Center for Oral Biology and Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | | | - Kathleen M. Maltby
- Center for Oral Biology and Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
| | - Ruland Jiang
- Center for Oral Biology and Department of Biomedical Genetics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA
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7
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Ching YH, Ghosh TK, Cross SJ, Packham EA, Honeyman L, Loughna S, Robinson TE, Dearlove AM, Ribas G, Bonser AJ, Thomas NR, Scotter AJ, Caves LSD, Tyrrell GP, Newbury-Ecob RA, Munnich A, Bonnet D, Brook JD. Mutation in myosin heavy chain 6 causes atrial septal defect. Nat Genet 2005; 37:423-8. [PMID: 15735645 DOI: 10.1038/ng1526] [Citation(s) in RCA: 189] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2004] [Accepted: 01/19/2005] [Indexed: 12/22/2022]
Abstract
Atrial septal defect is one of the most common forms of congenital heart malformation. We identified a new locus linked with atrial septal defect on chromosome 14q12 in a large family with dominantly inherited atrial septal defect. The underlying mutation is a missense substitution, I820N, in alpha-myosin heavy chain (MYH6), a structural protein expressed at high levels in the developing atria, which affects the binding of the heavy chain to its regulatory light chain. The cardiac transcription factor TBX5 strongly regulates expression of MYH6, but mutant forms of TBX5, which cause Holt-Oram syndrome, do not. Morpholino knock-down of expression of the chick MYH6 homolog eliminates the formation of the atrial septum without overtly affecting atrial chamber formation. These data provide evidence for a link between a transcription factor, a structural protein and congenital heart disease.
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Affiliation(s)
- Yung-Hao Ching
- Institute of Genetics, University of Nottingham, Queen's Medical Centre, Nottingham NG7 2UH, UK
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8
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Sharma PR, Anderson RH, Copp AJ, Henderson DJ. Spatiotemporal analysis of programmed cell death during mouse cardiac septation. ACTA ACUST UNITED AC 2004; 277:355-69. [PMID: 15052663 DOI: 10.1002/ar.a.20006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Cell death is thought to play an important role in mammalian cardiogenesis, although a precise map of its distribution during the crucial period of cardiac septation has so far been lacking. In this study, the spatiotemporal distribution of programmed cell death (PCD) during mouse cardiac septation is described between embryonic days 10.5 and 13.5. Two types of foci of cell death can be demonstrated in the developing heart. Those with high-intensity, with a PCD index greater than 1%, are clearly visible on individual TUNEL-assayed sections. Low-intensity foci, with a PCD index of less than 1%, become visible only following summation of data. High-intensity foci occur exclusively within the endocardial cushions of the outflow tract and atrioventricular region, appearing at the 52-54 somite stage (late E11.5), concomitant with the formation of the central mesenchymal mass. Low-intensity foci are present throughout the period of cardiac development from E10.5 to E13.5 and are frequently localized to regions of septation, such as the muscular ventricular septum and the mesenchymal cap of the primary atrial septum. Expression of Fas and FasL corresponds to these low-intensity foci, but not those with high-intensity, suggesting that activation of this death receptor may be specifically involved in molecular control of the low-intensity foci.
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Affiliation(s)
- Pundrique R Sharma
- Neural Development Unit, Institute of Child Health, University College London, London, United Kingdom
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9
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Rothenberg F, Fisher SA, Watanabe M. Sculpting the cardiac outflow tract. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2003; 69:38-45. [PMID: 12768656 DOI: 10.1002/bdrc.10007] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The cardiac outflow tract is the site of anomalies that affect a substantial proportion of individuals with congenital heart defects. The morphogenesis of this site is complex, and requires coordinated development of many cell types and tissues. It is therefore not surprising that developmental mistakes arise here, and that the steps and mechanisms of morphogenesis are still controversial and poorly understood, despite advances in molecular techniques. Recent findings have provided new insight into mechanisms of outflow tract morphogenesis, including clarification of its origins and the fate of cardiomyocytes, as well as invading cell populations. Application of new and old techniques and a wide range of approaches to tackle the unanswered questions about the outflow tract calls for collaboration among investigators from different disciplines including anatomists, physiologists, and molecular biologists.
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Affiliation(s)
- Florence Rothenberg
- Heart and Vascular Department, MetroHealth, Metrohealth Campus, Case Western Reserve University, School of Medicine, Cleveland, Ohio, USA
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10
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Abstract
Development of the heart is a complex process involving primary and secondary heart fields that are set aside to generate myocardial and endocardial cell lineages. The molecular inductions that occur in the primary heart field appear to be recapitulated in induction and myocardial differentiation of the secondary heart field, which adds the conotruncal segments to the primary heart tube. While much is now known about the initial steps and factors involved in induction of myocardial differentiation, little is known about induction of endocardial development. Many of the genes expressed by nascent myocardial cells, which then become committed to a specific heart segment, have been identified and studied. In addition to the heart fields, several other "extracardiac" cell populations contribute to the fully functional mature heart. Less is known about the genetic programs of extracardiac cells as they enter the heart and take part in cardiogenesis. The molecular/genetic basis of many congenital cardiac defects has been elucidated in recent years as a result of new insights into the molecular control of developmental events.
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Affiliation(s)
- Margaret L Kirby
- Department of Pediatrics, Division of Neonatology, Duke University Medical Center, Box 3179, Durham, NC 27710, USA.
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11
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Abstract
Heart morphogenesis comprises 2 major consecutive steps, viz. chamber formation followed by septation. Septation is the remodeling of the heart from a single-channel peristaltic pump to a dual-channel, synchronously contracting device with 1-way valves. In the human heart, septation occurs between 4 and 7 weeks of development. Cardiac looping and chamber formation bring the contributing structures into position to engage in septation. Cardiomyocytes that participate in chamber formation do not materially contribute to septation. The (re)discovery of the role of extracardiac mesenchymal tissue in atrioventricular septation, the appreciation that the formation of the right atrioventricular connection is more than a mere rightward expansion of the atrioventricular canal, the awareness that myocardium originating from the so-called anterior heart field regresses after its function as outflow-tract sphincter ceases, and the recent finding that the myocardialized proximal portion of the outflow-tract septum becomes the supraventricular crest have all significantly enhanced our understanding of the morphogenetic processes that contribute to septation. The bifurcation of the ventricular conduction system is the landmark that separates the contribution of the atrioventricular cushions and the outflow-tract ridges to septation and that divides the muscular ventricular septum in inlet, trabecular, and outlet portions.
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Affiliation(s)
- Wouter H Lamers
- Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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13
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Kim JS, Virágh S, Moorman AF, Anderson RH, Lamers WH. Development of the myocardium of the atrioventricular canal and the vestibular spine in the human heart. Circ Res 2001; 88:395-402. [PMID: 11230106 DOI: 10.1161/01.res.88.4.395] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To establish the morphogenetic mechanisms underlying formation and separation of the atrioventricular connections, we studied the remodeling of the myocardium of the atrioventricular canal and the extracardiac mesenchymal tissue of the vestibular spine in human embryonic hearts from 4.5 to 10 weeks of development. Septation of the atrioventricular junction is brought about by downgrowth of the primary atrial septum, fusion of the endocardial cushions, and forward expansion of the vestibular spine between atrial septum and cushions. The vestibular spine subsequently myocardializes to form the ventral rim of the oval fossa. The connection of the atrioventricular canal with the atria expands evenly. In contrast, the expression patterns of creatine kinase M and GlN2, markers for the atrioventricular and interventricular junctions, respectively, show that the junction of the canal with the right ventricle forms by local growth in the inner curvature of the heart. Growth of the caudal portion of the muscular ventricular septum to make contact with the inferior endocardial cushion occurs only after the canal has expanded rightward. The atrioventricular node develops from that part of the canal myocardium that retains its continuity with the ventricular myocardium.
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Affiliation(s)
- J S Kim
- Department of Anatomy & Embryology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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Wessels A, Anderson RH, Markwald RR, Webb S, Brown NA, Viragh S, Moorman AF, Lamers WH. Atrial development in the human heart: an immunohistochemical study with emphasis on the role of mesenchymal tissues. THE ANATOMICAL RECORD 2000; 259:288-300. [PMID: 10861362 DOI: 10.1002/1097-0185(20000701)259:3<288::aid-ar60>3.0.co;2-d] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The development of the atrial chambers in the human heart was investigated immunohistochemically using a set of previously described antibodies. This set included the monoclonal antibody 249-9G9, which enabled us to discriminate the endocardial cushion-derived mesenchymal tissues from those derived from extracardiac splanchnic mesoderm, and a monoclonal antibody recognizing the B isoform of creatine kinase, which allowed us to distinguish the right atrial myocardium from the left. The expression patterns obtained with these antibodies, combined with additional histological information derived from the serial sections, permitted us to describe in detail the morphogenetic events involved in the development of the primary atrial septum (septum primum) and the pulmonary vein in human embryos from Carnegie stage 14 onward. The level of expression of creatine kinase B (CK-B) was found to be consistently higher in the left atrial myocardium than in the right, with a sharp boundary between high and low expression located between the primary septum and the left venous valve indicating that the primary septum is part of the left atrial gene-expression domain. This expression pattern of CK-B is reminiscent of that of the homeobox gene Pitx2, which has recently been shown to be important for atrial septation in the mouse. This study also demonstrates a poorly appreciated role of the dorsal mesocardium in cardiac development. From the earliest stage investigated onward, the mesenchyme of the dorsal mesocardium protrudes into the dorsal wall of the primary atrial segment. This dorsal mesenchymal protrusion is continuous with a mesenchymal cap on the leading edge of the primary atrial septum. Neither the mesenchymal tissues of the dorsal protrusion nor the mesenchymal cap on the edge of the primary septum expressed the endocardial tissue antigen recognized by 249-9G9 at any of the stages investigated. The developing pulmonary vein uses the dorsal mesocardium as a conduit to reach the primary atrial segment. Initially, the pulmonary pit, which will becomes the portal of entry for the pulmonary vein, is located along the midline, flanked by two myocardial ridges. As development progresses, tissue remodeling results in the incorporation of the portal of entry of the pulmonary vein in left atrial myocardium, which is recognized because of its high level of creatine. Closure of the primary atrial foramen by the primary atrial septum occurs as a consequence of the fusion of these mesenchymal structures.
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Affiliation(s)
- A Wessels
- Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston 29425, USA.
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15
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Abstract
It is sometimes thought that formation of the atrioventricular septum is equated with fusion of the endocardial cushions and that failure of fusion can explain all deficiencies of atrioventricular septation. Clearly, this is simplistic, but the exact contribution of different primordia to atrioventricular septation is not well understood. To clarify this, we studied normal mouse embryos (days 10 to 15 of gestation), which were serially sectioned and examined by light microscopy. Another group of embryos was examined by scanning electron microscopy after microdissection. Our results show that development of the atrioventricular septal area is highly complex. Proper formation requires the following: remodeling of the inner heart curvature, rotation of the horns of the systemic venous sinus around the pulmonary portal, expansion of the right atrioventricular junction, formation of the muscular atrial and ventricular septa, bridging by the dextrodorsal outflow ridge and the superior endocardial cushion, fusion with the inferior margins of the venous valves, and formation of the mouth of the coronary sinus from the cranial muscular wall of the left sinus horn. Multiple primordia contribute to a central mesenchymal mass (the "septum intermedium"), including the mesenchyme on the leading edge of the primary atrial septum, the atrioventricular endocardial cushions, and the cap of mesenchyme on the spina vestibuli. Fusion of these components closes the ostium primum, completing atrial and atrioventricular septation. Additionally, the spina vestibuli has a mesodermal core, which contributes to the muscularization of the lower margin of the oval fossa. This contrasts with the formation of the upper rim, which occurs as a result of an infolding of the atrial wall itself.
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Affiliation(s)
- S Webb
- Department of Anatomy and Developmental Biology, St George's Hospital Medical School, London, UK.
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16
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Webb S, Brown NA, Wessels A, Anderson RH. Development of the murine pulmonary vein and its relationship to the embryonic venous sinus. Anat Rec (Hoboken) 1998; 250:325-34. [PMID: 9517849 DOI: 10.1002/(sici)1097-0185(199803)250:3<325::aid-ar7>3.0.co;2-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Arguments concerning the development of the pulmonary vein, and its relationship to the embryonic venous sinus (sinus venosus) have continued for well over a century. Recently, attention has again been focused on the origin of the pulmonary vein. It has been suggested that, whereas the pulmonary vein originates from the left atrium in humans, in all other vertebrates it originates from the venous sinus, with subsequent transfer to the left atrium. The nature of this transfer has not, however, been elucidated, although there is speculation that the pulmonary vein is "pinched off" from the left side of the embryonic venous sinus. METHODS We studied closely staged hearts of normal mouse embryos from a C57BL/6 x CBAcross days 10 and 11 of gestation (plug day = day 1). Two series of embryos were collected and fixed in 2% glutaraldehyde, 1% formaldehyde, buffered with 0.05 M sodium cacodylate pH 7.4 (adjusted to 330 mOsm with NaCl). One series was wax embedded, serially sectioned, and stained with Masson's trichrome. The second series was subject to microdissection and scanning electron microscopy. RESULTS The atrial component of the heart tube is attached to the body of the embryo by reflections of the atrial myocardial wall. The attachment can be considered, from the outset, as the heart stalk, with the myocardial-mesodermal connections forming a horseshoe of tissue that projects ventrally into the lumen of the atrium, surrounding a single evagination in the midline of the embryo. This heart stalk is cranial to the connections of the tributaries of the embryonic venous sinus and ventral to the foregut. When traced through its developmental stages, the evagination in the centre of the stalk, which we describe as the pulmonary pit, is seen to become the portal of entry for the developing pulmonary vein. CONCLUSIONS The heart stalk, representing the area used by the pulmonary vein to gain access to the heart, and analogous to the dorsal mesocardium, is, from the outset, discrete from the area occupied by the orifices of the horns of the embryonic venous sinus. The pulmonary vein does not, in the mouse, develop from the tissues that form the walls of the tributaries of the systemic venous sinus. Comparisons with other studies suggest that early events in the development of the pulmonary vein are likely to be the same in all mammals, including humans.
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Affiliation(s)
- S Webb
- Department of Anatomy and Developmental Biology, St. George's Hospital Medical School, London, UK
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17
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Gallego A, Durán AC, De Andrés AV, Navarro P, Muñoz-Chápuli R. Anatomy and development of the sinoatrial valves in the dogfish (Scyliorhinus canicula). Anat Rec (Hoboken) 1997; 248:224-32. [PMID: 9185988 DOI: 10.1002/(sici)1097-0185(199706)248:2<224::aid-ar9>3.0.co;2-s] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND We describe the adult anatomy and the development of the cardiac sinoatrial valves in the dogfish (Scyliorhinus canicula). METHODS We use scanning electron microscopy, histological and histochemical techniques in 39 hearts from embryos and adult specimens. RESULTS The sinoatrial valvular set of the adult dogfish is composed of two transverse valves laterally attached to the sinoatrial junction at their bases. Both valves are composed of two muscular layers, the sinusal and the atrial, whose histological features are similar to the cardiac wall which they face. Collagen bundles, elastic fibers and fibroblasts are present between the muscular layers. The extracellular matrix between the valvular layers also contains sulphated and non-sulphated glycosaminoglycans. The sinoatrial valves develop from two lateral infoldings of the cardiac wall. The left fold is deeper than the right, causing a shift of the sinoatrial communication to the right. The epicardium progressively covers the outer sinoatrial groove and the space between the folds becomes populated by mesenchymal cells. The posterior atrioventricular endocardial cushion is in contact with the base of the left fold until the embryo has about 40 mm TL. CONCLUSIONS The sinoatrial valves, in the dogfish, develop from lateral infoldings of the cardiac wall. This origin results in histological and histochemical differences between the two muscular layers which constitute the valves of the adult. The comparison of the sinoatrial valve morphogenesis between the dogfish and some higher vertebrates suggests that the right sinoatrial valve, but not the left, is homologous throughout the vertebrate phylogeny.
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Affiliation(s)
- A Gallego
- Department of Animal Biology, Faculty of Science, University of Málaga, Spain
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18
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Abstract
Septation of the tubular heart to form the multi-chambered heart involves endocardial cell mesenchymal transformation at discrete sites. These sites include the crests of endocardial cushions at the atrioventricular junction, crests of the spiral ridges within the outflow tract, and the leading edge of the atrial septum. The factors involved in this multi-step inductive process appear to include the neural cell adhesion molecule (NCAM). The down-regulation of NCAM coincident with mesenchymal transformation has been documented at the atrioventricular cushion tissue. In view of the function-regulation properties of polysialylated NCAM (PSA-NCAM), we hypothesized that this form of NCAM would be playing a role during the dramatic changes in cell-cell interactions occurring in the endocardium at the leading edge of the primary atrial septum. Chicken hearts at stages during primary atrial septum development were fixed with paraformaldehyde and either immunofluorescently stained for the light microscope analysis or immunoperoxidase stained for ultrastructural analysis. A monoclonal antibody to an NCAM polypeptide epitope (5E) was used to detect all forms of NCAM, while a monoclonal to the polysialic acid (5A5) was used to detect that subset of NCAM which is highly polysialylated (PSA-NCAM). By light microscope level analysis, an increase in immunostaining for NCAM and the appearance of PSA-NCAM was detected on embryonic chicken endocardial cells at the leading edge of the growing atrial septum. The ultrastructural analysis revealed that there is also a change in the pattern of NCAM and PSA-NCAM from a polarized localization to a more ubiquitous distribution over the endocardial cell surface as these cells send out processes, form multiple layers, and sink or move into the underlying extracellular matrix. PSA-NCAM was also detected along cell appositions of cells within the matrix. Both NCAM and PSA-NCAM levels were reduced on cells deep within the matrix. These findings indicate that during primary atrial septation, PSA-NCAM may be deployed on endocardial epithelial cells in order to down-regulate cell-cell interactions and allow the detachment and migration of some of these cells into the underlying matrix.
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Affiliation(s)
- M Gerety
- Department of Pediatrics, Rainbow Babies and Childrens Hospital, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
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Muñoz-Chápuli R, Macías D, Ramos C, Gallego A, De Andrés V. Development of the subepicardial mesenchyme and the early cardiac vessels in the dogfish (Scyliorhinus canicula). ACTA ACUST UNITED AC 1996. [DOI: 10.1002/(sici)1097-010x(19960601/15)275:2/3<95::aid-jez4>3.0.co;2-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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20
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Roman J, McDonald JA. Expression of fibronectin, the integrin alpha 5, and alpha-smooth muscle actin in heart and lung development. Am J Respir Cell Mol Biol 1992; 6:472-80. [PMID: 1533775 DOI: 10.1165/ajrcmb/6.5.472] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The developmentally regulated expression of fibronectin (FN) in developing organs and FN's ability to stimulate cell migration and differentiation in vitro suggest a role in organogenesis. We examined the distribution of FN and the alpha 5 subunit of its receptor, the integrin alpha 5 beta 1, in the lungs and hearts of murine embryos at 11, 13, 16, and 18 days of gestation. In the lung, FN staining was present in the mesenchyme and parabronchial cells at day 11, increased at day 13, and decreased after day 16. Increases in FN coincided with the period of branching morphogenesis, and FN was concentrated at areas of airway bifurcation, suggesting a role for FN in cleft formation. The alpha 5 subunit appeared later at 13 days, co-distributing with FN only in well-developed primary bronchioles. At all stages, alpha-smooth muscle actin expression correlated temporally and spatially with that of the alpha 5 subunit. In the heart, staining for FN, the alpha 5 subunit, and alpha-smooth muscle actin were present at day 11 and increased at day 13. FN was present in the outflow tract and developing atria and ventricles, where it was concentrated in the outer layer or visceral pericardium. Interestingly, alpha 5 was detected at the inner layer, the endothelium, lining the outflow tract and atrioventricular cushions where endothelial cells migrate into the cardiac jelly in the process of epithelial-mesenchymal transformation. This suggests a potential role for alpha 5 beta 1 and FN in ventricular septation and valve formation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J Roman
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
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21
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Gilloteaux J, Linz D. Endocardial surface and atrial morphological changes during development and aging. THE AMERICAN JOURNAL OF ANATOMY 1989; 186:161-72. [PMID: 2816783 DOI: 10.1002/aja.1001860206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Light, scanning, and transmission electron microscopic observations related to morphological changes of the right atrium as well as the atrial endocardium during development (15th embryonic day and 1 day old) and aging (560 days old) in the Syrian hamster were described and correlated. From the fetus to the adult, the atrial endocardium differentiates in parallel with, or in response to, the subjacent proliferating myocytes in the atrial wall and the trabeculae. Simultaneously, the atrium compartmentalizes grossly into a main chamber and an appendicular region. There is a progressive differentiation from a rudimentary, open chamber with primitive mural ridges in the fetal atria to a distinct, separate, atrial main chamber and appendage with a dense network of trabeculae in the adult. The fetal and neonatal endocardial, endothelial cells are convex with a central nuclear bulging and attenuated cytoplasmic extensions; the adult endocardium shows a squamous endothelium. Two cell surface specializations were observed in all age groups: microvilli and blebs or cytoplasmic protrusions. The general atrial morphology and surface endocardial changes were correlated with growth and the role of the endocardial endothelium as a barrier which controls metabolic exchanges, including the transport of atrial natriuretic factor, between the myocytes and the blood. This endothelial function appears to be essential in the fetal and neonatal age groups since no blood vessels are detected in these groups.
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Affiliation(s)
- J Gilloteaux
- Department of Anatomy, Northeastern Ohio Universities College of Medicine, Rootstown, Ohio 44272
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Arciniegas E, Servin M, Argüello C, Mota M. Development of the aorta in the chick embryo: structural and ultrastructural study. Atherosclerosis 1989; 76:219-35. [PMID: 2730719 DOI: 10.1016/0021-9150(89)90106-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
A structural and ultrastructural study was designed to analyze systematically the cellular events which take place in the aortic wall between days 7 and 21 of chick embryo development. Between days 7 and 18, increase in total diameter, number of cell layers, and aortic wall thickness are highly correlated, whereas between days 18 and 21 the total diameter increase is correlated mainly with an increase in vessel lumen diameter. Cell layers of smooth muscle cells showing an immature or synthetic phenotype arise from progressive association and organization of mesenchymal cells originated from an endothelial activation process in which a hyaluronic acid-rich extracellular matrix seems to be involved. It is suggested that the process of endothelial activation takes place between days 7 and 18 of embryonic development provided that within that period the typical cellular events which are involved in such a process take place (hypertrophy, reorientation, invagination, mitotic activity, acquisition of migratory appendages, endothelial detachment and incorporation into adjacent spaces). This endothelial activation has been recognized as a selective multiphasic process required for the transition of endothelial cells into mesenchyma.
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Affiliation(s)
- E Arciniegas
- Instituto de Medicina Experimental, Facultad de Medicina, Universidad Central de Venezuela, Caracas
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