MORPHOGENESIS IN PREIMPLANTATION EMBRYO

许多常见的出生缺陷是由形态发生缺陷引起的。我们的初选 工作假说是形态发生取决于细胞的极性，这是 由细胞表面-细胞骨架相互作用建立和维持的 对不对称的细胞-细胞接触很敏感。我们的目标是 用小鼠胚泡形成作为研究这一假说的依据 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)。本项目的重点是 空化的形态发生细节，这对滋养外胚层/ICM至关重要 差异化。 我提出了新陈代谢空化模型来解释空化和 产生新生的胚胎液。这款车的独特之处在于 包括： 1)胚泡积液的产生取决于细胞质的极性 由细胞器的不对称分布(线粒体和 脂滴)，沿着相对的细胞表面堆积。 2)细胞质极性的维持依赖于： A.区分游离态和反义态的质膜性质 细胞表面； B.对不对称敏感的细胞表面-细胞骨架相互作用 细胞-细胞接触； C.进入自由(心尖)表面并离开的跨细胞离子电流 具有不对称细胞-细胞的卵裂球的相对(基侧)表面 触点(桑囊胚的外部卵裂球)。 3)囊胚液中的水分是脂肪的β-氧化作用的结果。 水滴。特定的目标将考验新陈代谢的这些特征 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 特定的质膜结构域与干扰治疗 细胞骨架元素和细胞表面-细胞骨架联合。效应 细胞器分布将通过形态计量学分析在 电子显微镜(EM)水平。分离的卵裂球将是 受到电场的影响，以获得关于分子如何 分离到特定的质膜结构域。脂类分解代谢 空化将通过在电磁水平上的形态计量分析来量化。

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.