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Cite this page: Hill, M.A. (2019, August 17) Embryology Developmental Mechanisms. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Developmental_Mechanisms
What does time mean in development?
Ebisuya M1, Briscoe J2. Author information Abstract Biology is dynamic. Timescales range from frenetic sub-second ion fluxes and enzymatic reactions to the glacial millions of years of evolutionary change. Falling somewhere in the middle of this range are the processes we usually study in development: cell division and differentiation, gene expression, cell-cell signalling, and morphogenesis. But what sets the tempo and manages the order of developmental events? Are the order and tempo different between species? How is the sequence of multiple events coordinated? Here, we discuss the importance of time for developing embryos, highlighting the necessity for global as well as cell-autonomous control. New reagents and tools in imaging and genomic engineering, combined with in vitro culture, are beginning to offer fresh perspectives and molecular insight into the origin and mechanisms of developmental time. PMID: 29945985 PMCID: PMC6031406 DOI: 10.1242/dev.164368
Scaling of pattern formations and morphogen gradients
Dev Growth Differ. 2017 Jan;59(1):41-51. doi: 10.1111/dgd.12337. Epub 2017 Jan 17.
Abstract The concentration gradient of morphogens provides positional information for an embryo and plays a pivotal role in pattern formation of tissues during the developmental processes. Morphogen-dependent pattern formations show robustness despite various perturbations. Although tissues usually grow and dynamically change their size during histogenesis, proper patterns are formed without the influence of size variations. Furthermore, even when the blastula embryo of Xenopus laevis is bisected into dorsal and ventral halves, the dorsal half of the embryo leads to proportionally patterned half-sized embryos. This robustness of pattern formation despite size variations is termed as scaling. In this review, I focused on the morphogen-dependent dorsal-ventral axis formation in Xenopus and described how morphogens form a proper gradient shape according to the embryo size. © 2017 Japanese Society of Developmental Biologists.
KEYWORDS: Xenopus laevis ; Dorsal-ventral axis; morphogen gradient; morphogen scaling; pattern formation PMID 28097650 DOI: 10.1111/dgd.12337
Getting to know your neighbor: cell polarization in early embryos
J Cell Biol. 2014 Sep 29;206(7):823-32. doi: 10.1083/jcb.201407064.
Abstract Polarization of early embryos along cell contact patterns--referred to in this paper as radial polarization--provides a foundation for the initial cell fate decisions and morphogenetic movements of embryogenesis. Although polarity can be established through distinct upstream mechanisms in Caenorhabditis elegans, Xenopus laevis, and mouse embryos, in each species, it results in the restriction of PAR polarity proteins to contact-free surfaces of blastomeres. In turn, PAR proteins influence cell fates by affecting signaling pathways, such as Hippo and Wnt, and regulate morphogenetic movements by directing cytoskeletal asymmetries. © 2014 Nance.
The roles and regulation of multicellular rosette structures during morphogenesis
Development. 2014 Jul;141(13):2549-58. doi: 10.1242/dev.101444.
Harding MJ1, McGraw HF2, Nechiporuk A3.
Multicellular rosettes have recently been appreciated as important cellular intermediates that are observed during the formation of diverse organ systems. These rosettes are polarized, transient epithelial structures that sometimes recapitulate the form of the adult organ. Rosette formation has been studied in various developmental contexts, such as in the zebrafish lateral line primordium, the vertebrate pancreas, the Drosophila epithelium and retina, as well as in the adult neural stem cell niche. These studies have revealed that the cytoskeletal rearrangements responsible for rosette formation appear to be conserved. By contrast, the extracellular cues that trigger these rearrangements in vivo are less well understood and are more diverse. Here, we review recent studies of the genetic regulation and cellular transitions involved in rosette formation. We discuss and compare specific models for rosette formation and highlight outstanding questions in the field. © 2014. Published by The Company of Biologists Ltd. KEYWORDS: Drosophila epithelium; Morphogenesis; Myosin II; Rosette; Zebrafish lateral line
Cilia, calcium and the basis of left-right asymmetry
BMC Biol. 2012 Dec 19;10:102. doi: 10.1186/1741-7007-10-102.
Norris DP. Source Mammalian Genetics Unit, MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire, OX11 0RD, UK. email@example.com. Abstract ABSTRACT: The clockwise rotation of cilia in the developing mammalian embryo drives a leftward flow of liquid; this genetically regulated biophysical force specifies left-right asymmetry of the mammalian body. How leftward flow is interpreted and information propagated to other tissues is the subject of debate. Four recent papers have shed fresh light on the possible mechanisms.
Extracellular matrix and cytoskeletal dynamics during branching morphogenesis
Organogenesis. 2012 Apr-Jun;8(2):56-64. doi: 10.4161/org.19813. Epub 2012 Apr 1.
Kim HY, Nelson CM. Source Department of Chemical and Biological Engineering, Princeton University; Princeton, NJ USA.
Branching morphogenesis is a fundamental developmental process which results in amplification of epithelial surface area for exchanging molecules in organs including the lung, kidney, mammary gland and salivary gland. These complex tree-like structures are built by iterative rounds of simple routines of epithelial morphogenesis, including bud formation, extension, and bifurcation, that require constant remodeling of the extracellular matrix (ECM) and the cytoskeleton. In this review, we highlight the current understanding of the role of the ECM and cytoskeletal dynamics in branching morphogenesis across these different organs. The cellular and molecular mechanisms shared during this morphogenetic process provide insight into the development of other branching organs. PMID 22609561
The bending of cell sheets--from folding to rolling
BMC Biol. 2011 Dec 29;9:90. Keller R, Shook D. Source Department of Biology, 241 Gilmer Hall, University of Virginia, Charlottesville, VA 22904, USA. firstname.lastname@example.org
The bending of cell sheets plays a major role in multicellular embryonic morphogenesis. Recent advances are leading to a deeper understanding of how the biophysical properties and the force-producing behaviors of cells are regulated, and how these forces are integrated across cell sheets during bending. We review work that shows that the dynamic balance of apical versus basolateral cortical tension controls specific aspects of invagination of epithelial sheets, and recent evidence that tissue expansion by growth contributes to neural retinal invagination in a stem cell-derived, self-organizing system. Of special interest is the detailed analysis of the type B inversion in Volvox reported in BMC Biology by Höhn and Hallmann, as this is a system that promises to be particularly instructive in understanding morphogenesis of any monolayered spheroid system. © 2011 Keller and Shook; licensee BioMed Central Ltd.