The Experts below are selected from a list of 108 Experts worldwide ranked by ideXlab platform
Amanda J G Dickinson - One of the best experts on this subject based on the ideXlab platform.
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role of jnk during Buccopharyngeal Membrane perforation the last step of embryonic mouth formation
Developmental Dynamics, 2017Co-Authors: Nathalie S Houssin, Navaneetha Krishnan Bharathan, Stephen D Turner, Amanda J G DickinsonAbstract:Background: The Buccopharyngeal Membrane is a thin layer of cells covering the embryonic mouth. The perforation of this structure creates an opening connecting the external and the digestive tube which is essential for oral cavity formation. In humans, persistence of the Buccopharyngeal Membrane can lead to orofacial defects such as choanal atresia, oral synechiaes and cleft palate. Little is known about the causes of a persistent Buccopharyngeal Membrane and importantly how this structure ruptures. Results: We have determined that Xenopus embryos deficient JNK signaling, using antisense and pharmacological approaches, have a persistent Buccopharyngeal Membrane. JNK deficient embryos have decreased cell division and increased cellular stress and apoptosis. However, altering these processes independently of JNK did not affect Buccopharyngeal Membrane perforation. JNK deficient embryos also have increased intercellular adhesion and defects in e-cadherin localization. Conversely, embryos with overactive JNK have epidermal fragility, increased E-cadherin internalization and increased Membrane localized clathrin. In the Buccopharyngeal Membrane, clathrin is colocalized with active JNK. Further, inhibition of endocytosis results in a persistent Buccopharyngeal Membrane, mimicking the JNK deficient phenotype. Conclusions: The results of this study suggest that JNK has a role in the disassembly adherens junctions via endocytosis that is required during Buccopharyngeal Membrane perforation. This article is protected by copyright. All rights reserved.
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Using frogs faces to dissect the mechanisms underlying human orofacial defects.
Seminars in Cell & Developmental Biology, 2016Co-Authors: Amanda J G DickinsonAbstract:In this review I discuss how Xenopus laevis is an effective model to dissect the mechanisms underlying orofacial defects. This species has been particularly useful in studying the understudied structures of the developing face including the embryonic mouth and primary palate. The embryonic mouth is the first opening between the foregut and the environment and is critical for adult mouth development. The final step in embryonic mouth formation is the perforation of a thin layer of tissue covering the digestive tube called the Buccopharyngeal Membrane. When this tissue does not perforate in humans it can pose serious health risks for the fetus and child. The primary palate forms just dorsal to the embryonic mouth and in non-amniotes it functions as the roof of the adult mouth. Defects in the primary palate result in a median oral cleft that appears similar across the vertebrates. In humans, these median clefts are often severe and surgically difficult to repair. Xenopus has several qualities that make it advantageous for craniofacial research. The free living embryo has an easily accessible face and we have also developed several new tools to analyze the development of the region. Further, Xenopus is readily amenable to chemical screens allowing us to uncover novel gene-environment interactions during orofacial development, as well as to define underlying mechanisms governing such interactions. In conclusion, we are utilizing Xenopus in new and innovative ways to contribute to craniofacial research.
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Development of the primary mouth in Xenopus laevis
Developmental Biology, 2006Co-Authors: Amanda J G Dickinson, Hazel SiveAbstract:The initial opening between the gut and the outside of the deuterostome embryo breaks through at the extreme anterior. This region is unique in that ectoderm and endoderm are directly juxtaposed, without intervening mesoderm. This opening has been called the stomodeum, Buccopharyngeal Membrane or oral cavity at various stages of its formation, however, in order to clarify its function, we have termed this the “primary mouth”. In vertebrates, the neural crest grows around the primary mouth to form the face and a “secondary mouth” forms. The primary mouth then becomes the pharyngeal opening. In order to establish a molecular understanding of primary mouth formation, we have begun to examine this process during Xenopus laevis development. An early step during this process occurs at tailbud and involves dissolution of the basement Membrane between the ectoderm and endoderm. This is followed by ectodermal invagination to create the stomodeum. A subsequent step involves localized cell death in the ectoderm, which may lead to ectodermal thinning. Subsequently, ectoderm and endoderm apparently intercalate to generate one to two cell layers. The final step is perforation, where (after hatching) the primary mouth opens. Fate mapping has defined the ectodermal and endodermal regions that will form the primary mouth. Extirpations and transplants of these and adjacent regions indicate that, at tailbud, the oral ectoderm is not specifically required for primary mouth formation. In contrast, underlying endoderm and surrounding regions are crucial, presumably sources of necessary signals. This study indicates the complexity of primary mouth formation, and lays the groundwork for future molecular analyses of this important structure.
Ramesh Chandra - One of the best experts on this subject based on the ideXlab platform.
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persistent Buccopharyngeal Membrane a report of two cases
Plastic and Reconstructive Surgery, 1996Co-Authors: Rajiv Agarwal, Pramod Kumar, G S Kalra, Shashi Bhushan, Ramesh ChandraAbstract:Persistent Buccopharyngeal Membrane is an extremely rare clinical entity that can be diagnosed easily by simple examination of the oral cavity and confirmed by a lateral contrast x-ray. The abnormality can be easily corrected surgically.
Rajiv Agarwal - One of the best experts on this subject based on the ideXlab platform.
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persistent Buccopharyngeal Membrane a report of two cases
Plastic and Reconstructive Surgery, 1996Co-Authors: Rajiv Agarwal, Pramod Kumar, G S Kalra, Shashi Bhushan, Ramesh ChandraAbstract:Persistent Buccopharyngeal Membrane is an extremely rare clinical entity that can be diagnosed easily by simple examination of the oral cavity and confirmed by a lateral contrast x-ray. The abnormality can be easily corrected surgically.
A. C. Gittenberger-de Groot - One of the best experts on this subject based on the ideXlab platform.
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The development of the myocardium and endocardium in mouse embryos
Anatomy and Embryology, 1992Co-Authors: M. C. Deruiter, R. E. Poelmann, I. Vanderplas-de Vries, M. M. T. Mentink, A. C. Gittenberger-de GrootAbstract:The formation of the single heart tube by hypothetical fusion of two separately developed heart tubes is re-investigated, because this intricate process is ambiguously and often incompletely described. To gain a better insight into this problem ten mouse embryos ranging from 7.5 to 8.5 days of development (presomite to 6 somites) were serially sectioned (1 μm) and reconstructed graphically. Twenty mouse embryos of comparative ages, were studied by scanning electron microscopy. Two large embryonic mesodermal compartments, derived from the primitive streak, extend rostrally on either side of the embryonic axis, and meet in front of the Buccopharyngeal Membrane. In each compartment a coelomic cavity develops, splitting the mesoderm into a splanchnic and somatic layer. The splanchnic mesoderm differentiates into a layer of cuboidal splanchnic mesothelial cells (promyocardium) and a subjacent plexus of elongated endothelial cells (proendocardium). Before the 1-somite stage the left and right splanchnic mesoderm are separated in front of the Buccopharyngeal Membrane by a thickening of the yolk sac endoderm. The splanchnic mesoderm then fuses, forming a single horseshoe-shaped heart primordium consisting of a promyocardial layer and a subjacent vascular plexus. Until the 2-somite stage both coelomic cavities remain separated by a bilayer of squamous somatic mesothelial cells (‘mesocardium’). The plexus of endothelial cells that forms the proendocardium, also seems to be the source of the lining of the vitelline veins, the pharyngeal arch arteries and the dorsal aortae. The relatively close adherence of endoderm to the medial part of the horseshoeshaped heart primordium, combined with a bilateral accumulation of cardiac jelly, is suggestive of a double heart tube. However, promyocardium and proendocardium are both translocated as one horseshoe-shaped layer, thus fusion of the left and right parts of the heart primordium does not occur.
M. C. Deruiter - One of the best experts on this subject based on the ideXlab platform.
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The development of the myocardium and endocardium in mouse embryos
Anatomy and Embryology, 1992Co-Authors: M. C. Deruiter, R. E. Poelmann, I. Vanderplas-de Vries, M. M. T. Mentink, A. C. Gittenberger-de GrootAbstract:The formation of the single heart tube by hypothetical fusion of two separately developed heart tubes is re-investigated, because this intricate process is ambiguously and often incompletely described. To gain a better insight into this problem ten mouse embryos ranging from 7.5 to 8.5 days of development (presomite to 6 somites) were serially sectioned (1 μm) and reconstructed graphically. Twenty mouse embryos of comparative ages, were studied by scanning electron microscopy. Two large embryonic mesodermal compartments, derived from the primitive streak, extend rostrally on either side of the embryonic axis, and meet in front of the Buccopharyngeal Membrane. In each compartment a coelomic cavity develops, splitting the mesoderm into a splanchnic and somatic layer. The splanchnic mesoderm differentiates into a layer of cuboidal splanchnic mesothelial cells (promyocardium) and a subjacent plexus of elongated endothelial cells (proendocardium). Before the 1-somite stage the left and right splanchnic mesoderm are separated in front of the Buccopharyngeal Membrane by a thickening of the yolk sac endoderm. The splanchnic mesoderm then fuses, forming a single horseshoe-shaped heart primordium consisting of a promyocardial layer and a subjacent vascular plexus. Until the 2-somite stage both coelomic cavities remain separated by a bilayer of squamous somatic mesothelial cells (‘mesocardium’). The plexus of endothelial cells that forms the proendocardium, also seems to be the source of the lining of the vitelline veins, the pharyngeal arch arteries and the dorsal aortae. The relatively close adherence of endoderm to the medial part of the horseshoeshaped heart primordium, combined with a bilateral accumulation of cardiac jelly, is suggestive of a double heart tube. However, promyocardium and proendocardium are both translocated as one horseshoe-shaped layer, thus fusion of the left and right parts of the heart primordium does not occur.
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The development of the myocardium and endocardium in mouse embryos. Fusion of two heart tubes
Anatomy and Embryology, 1992Co-Authors: M. C. Deruiter, M. M. T. Mentink, Robert E. Poelmann, I. Vanderplas-de Vries, A.c. Gittenberger-de GrootAbstract:The formation of the single heart tube by hypothetical fusion of two separately developed heart tubes is re-investigated, because this intricate process is ambiguously and often incompletely described. To gain a better insight into this problem ten mouse embryos ranging from 7.5 to 8.5 days of development (presomite to 6 somites) were serially sectioned (1 μm) and reconstructed graphically. Twenty mouse embryos of comparative ages, were studied by scanning electron microscopy. Two large embryonic mesodermal compartments, derived from the primitive streak, extend rostrally on either side of the embryonic axis, and meet in front of the Buccopharyngeal Membrane. In each compartment a coelomic cavity develops, splitting the mesoderm into a splanchnic and somatic layer. The splanchnic mesoderm differentiates into a layer of cuboidal splanchnic mesothelial cells (promyocardium) and a subjacent plexus of elongated endothelial cells (proendocardium). Before the 1-somite stage the left and right splanchnic mesoderm are separated in front of the Buccopharyngeal Membrane by a thickening of the yolk sac endoderm. The splanchnic mesoderm then fuses, forming a single horseshoe-shaped heart primordium consisting of a promyocardial layer and a subjacent vascular plexus. Until the 2-somite stage both coelomic cavities remain separated by a bilayer of squamous somatic mesothelial cells (‘mesocardium’). The plexus of endothelial cells that forms the proendocardium, also seems to be the source of the lining of the vitelline veins, the pharyngeal arch arteries and the dorsal aortae. The relatively close adherence of endoderm to the medial part of the horseshoeshaped heart primordium, combined with a bilateral accumulation of cardiac jelly, is suggestive of a double heart tube. However, promyocardium and proendocardium are both translocated as one horseshoe-shaped layer, thus fusion of the left and right parts of the heart primordium does not occur.
