组织胚胎学-文献订阅-三峡大学图书馆

摘要： Morphogen gradients pattern tissues and organs during development. When morphogen production is spatially restricted, diffusion and degradation are sufficient to generate sharp concentration gradients. It is less clear how sharp gradients can arise within the source of a broadly expressed morphogen. A recent solution relies on localized production of an inhibitor outside the domain of morphogen production, which effectively redistributes (shuttles) and concentrates the morphogen within its expression domain. Here, we study how a sharp gradient is established without a localized inhibitor, focusing on early dorsoventral patterning of the Drosophila embryo, where an active ligand and its inhibitor are concomitantly generated in a broad ventral domain. Using theory and experiments, we show that a sharp Toll activation gradient is produced through "self-organized shuttling," which dynamically relocalizes inhibitor production to lateral regions, followed by inhibitor-dependent ventral shuttling of the activating ligand Spatzle. Shuttling may represent a general paradigm for patterning early embryos.

民办高校应用型人才培养研究——组织胚胎学教育模式改革探讨

刘冠兰吴长初袁衡罗文奇赵品张晓东

长沙医学院组织胚胎学教研室湖南长沙 410219

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Extracellular matrix assembly and 3D organization during paraxial mesoderm development in the chick embryo

Rifes, Pedro Thorsteinsdottir, Solveig

Univ Lisbon Fac Ciencias Dept Biol Anim Ctr Biol Ambiental P-1749016 Lisbon PortugalInst Gulbenkian Ciencias Oeiras Portugal

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关键词： Paraxial mesoderm Somite development 3D reconstruction Fibronectin Laminin Extracellular matrix Morphogenesis Chick embryo

摘要： The extracellular matrix (ECM) is a major player in the microenvironment governing morphogenesis. However, much is yet to be known about how matrix composition and architecture changes as it influences major morphogenetic events. Here we performed a detailed, 3D analysis of the distribution of two ECM components, fibronectin and laminin, during the development of the chick paraxial mesoderm. By resorting to whole mount double immunofluorescence and confocal microscopy, we generated a detailed 3D map of the two ECM components, revealing their supra-cellular architecture in vivo, while simultaneously retaining high resolution cellular detail. We show that fibronectin assembly occurs at the surface of the presomitic mesoderm (PSM), where a gradual increase in the complexity of the fibronectin matrix accompanies PSM maturation. In the rostral PSM, where somites form, fibronectin fibrils are thick and densely packed and some occupy the cleft which comes to separate the newly formed somite from the PSM. Our 3D approach revealed that laminin matrix assembly starts at the PSM surface as small dispersed patches, which are always localized closer to cells than the fibronectin matrix. These patches gradually grow and coalesce with neighboring patches, but do not generate a continuous laminin sheet, not even on epithelial somites and dermomyotome, suggesting that these epithelia develop in contact with a fenestrated laminin matrix. Unexpectedly, as the somite differentiates, its fibronectin and laminin matrices are maintained, thus initially containing both the epithelial dermomyotome and the mesenchymal sclerotome within the somite segment. Our analysis provides unprecedented details of the progressive in vivo assembly and 3D architecture of fibronectin and laminin matrices during paraxial mesoderm development. These data are consistent with the hypothesis that progressive ECM assembly and subsequent 3D organization are active driving and containing forces during tissue develo

学生自主授课法在组织学与胚胎学实验教学中的探索和实践

马永臻庄园

山东医学高等专科学校组织学与胚胎学教研室临沂276000

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