MORPHOGENESIS IN PREIMPLANTATION EMBRYO

许多常见的出生缺陷是由形态发生缺陷引起的。 我们的首要 工作假设是形态发生取决于细胞极性， 通过细胞表面-细胞骨架相互作用建立和维持， 对不对称的细胞间接触很敏感。 我们的目标是 使用小鼠胚泡形成作为 哺乳动物形态发生的实验模型。 囊胚形成 需要两个相互关联的事件，1）空化和2）分化 滋养外胚层和内细胞团（ICM）。 该项目的重点是 空化的形态发生细节，这对滋养外胚层/ICM至关重要 分化 我提出了代谢空化模型来解释空化， 产生新生囊胚腔液。 这款车型的独特之处在于 是： 1)新生囊胚腔液的产生取决于细胞质极性 由细胞器（线粒体和 脂滴），其沿沿着的细胞表面积聚。 2)细胞质极性的维持取决于： a.区分游离和贴壁的质膜性质 细胞表面; B.细胞表面-细胞骨架相互作用，对不对称 细胞-细胞接触; C.进入游离（顶端）表面并离开 具有不对称细胞-细胞的卵裂球的并置（基底外侧）表面 接触（桑椹胚的外卵裂球）。 3)新生囊胚腔液中的水是脂质β-氧化的结果 水滴。 具体目标将测试代谢的这些功能 空化模型 将使用植物凝集素 （免疫荧光/免疫过氧化物酶技术）选择性标记 特异性质膜结构域与处理一起破坏 细胞骨架元件和细胞表面-细胞骨架关联。 影响 细胞器分布将通过形态测定分析进行定量， 电子显微镜（EM）水平。 分离的卵裂球 施加电场以获得分子如何 分离到特定的质膜区域。 脂质代谢 将通过EM水平的形态测定分析来定量空化。

Many common birth defects result from defective morphogenesis. Our primary working hypothesis is that morphogenesis depends on cell polarity, which is established and maintained by cell surface-cytoskeletal interactions that are sensitive to asymmetric cell-cell contacts. Our objective is to investigate this hypothesis using mouse blastocyst formation as an experimental model of mammalian morphogenesis. Blastocyst formation entails two interrelated events, 1) cavitation and 2) differentiation of trophectoderm and inner cell mass (ICM). This project focuses on the morphogenetic details of cavitation, which is critical to trophectoderm/ICM differentiation. I have proposed the Metabolic Cavitation Model to explain cavitation and production of nascent blastocoele fluid. The unique features of this model are: 1) Production of nascent blastocoele fluid depends on cytoplasmic polarity consisting of the asymmetric distribution of organelles (mitochondria and lipid droplets) that accumulate along apposed cell surfaces. 2) Maintenance of cytoplasmic polarity depends on: a. properties of the plasma membrane that distinguish free- from apposed cell surfaces; b. cell surface-cytoskeletal interactions that are sensitive to asymmetric cell-cell contacts; c. transcellular ion currents that enter free (apical) surfaces and leave apposed (basolateral) surfaces of blastomeres having asymmetric cell-cell contacts (the outer blastomeres of the morula). 3) Water in nascent blastocoele fluid results from beta-oxidation of lipid droplets. The Specific Aims will test these features of the Metabolic Cavitation Model. Plant lectins will be used (immunofluorescence/immunoperoxidase techniques) to selectively label specific plasma membrane domains together with treatments to disrupt cytoskeletal elements and cell surface-cytoskeletal associations. Effects on organelle distribution will be quantitated by morphometric analyses at the electron microscopic (EM) level. Isolated blastomeres will be subjected to electric fields to obtain information on how molecules are segregated to specific plasma membrane domains. Lipid catabolism during cavitation will be quantitated by morphometric analyses at the EM level.