Abstract Much of the scientific knowledge on oocyte maturation, fertilization, and embryonic development has come from the experiments using gametes of marine organisms that reproduce by external fertilization. In particular, echinoderm eggs have enabled the study of structural and biochemical changes related to meiotic maturation and fertilization owing to the abundant availability of large and transparent oocytes and eggs. Thus, in vitro studies of oocyte maturation and sperm-induced egg activation in starfish are carried out under experimental conditions that resemble those occurring in nature. During the maturation process, immature oocytes of starfish are released from the prophase of the first meiotic division, and acquire the competence to be fertilized through a highly programmed sequence of morphological and physiological changes at the oocyte surface. In addition, the changes in the cortical and nuclear regions are essential for normal and monospermic fertilization. This review summarizes the current state of research on the cortical actin cytoskeleton in mediating structural and physiological changes during oocyte maturation and sperm and egg activation in starfish and sea urchin. The common denominator in these studies with echinoderms is that exquisite rearrangements of the egg cortical actin filaments play pivotal roles in gamete interactions, Ca2+ signaling, exocytosis of cortical granules, and control of monospermic fertilization. In this review, we also compare findings from studies using invertebrate eggs with what is known about the contributions made by the actin cytoskeleton in mammalian eggs. Since the cortical actin cytoskeleton affects microvillar morphology, movement, and positioning of organelles and vesicles, and the topography of the egg surface, these changes have impacts on the fertilization process, as has been suggested by recent morphological studies on starfish oocytes and eggs using scanning electron microscopy. Drawing the parallelism between vitelline layer of echinoderm eggs and the zona pellucida of mammalian eggs, we also discuss the importance of the egg surface in mediating monospermic fertilization. Graphical abstract

中文翻译：

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卵母细胞成熟和受精的细胞和分子方面：肌动蛋白细胞骨架的视角。


摘要 关于卵母细胞成熟、受精和胚胎发育的许多科学知识都来自使用通过外部受精繁殖的海洋生物的配子进行的实验。特别是，由于大量透明的卵母细胞和卵子的存在，棘皮动物卵使得研究与减数分裂成熟和受精相关的结构和生化变化成为可能。因此，海星卵母细胞成熟和精子诱导的卵子激活的体外研究是在类似于自然界发生的实验条件下进行的。在成熟过程中，海星的未成熟卵母细胞从第一次减数分裂前期释放出来，并通过卵母细胞表面高度编程的形态和生理变化序列获得受精能力。此外，皮质和核区域的变化对于正常和单精子受精至关重要。本文总结了皮质肌动蛋白细胞骨架在海星和海胆卵母细胞成熟以及精子和卵子激活过程中介导结构和生理变化的研究现状。这些棘皮动物研究的共同点是卵皮质肌动蛋白丝的精细重排在配子相互作用、Ca2+信号传导、皮质颗粒的胞吐作用和单精子受精的控制中发挥着关键作用。在这篇综述中，我们还将使用无脊椎动物卵的研究结果与已知的哺乳动物卵中肌动蛋白细胞骨架的贡献进行了比较。 由于皮质肌动蛋白细胞骨架影响微绒毛的形态、细胞器和囊泡的运动和定位以及卵表面的地形，因此这些变化对受精过程有影响，正如最近使用扫描对海星卵母细胞和卵进行的形态学研究所表明的那样电子显微镜。借鉴棘皮动物卵的卵黄层与哺乳动物卵的透明带的相似性，我们还讨论了卵表面在介导单精子受精中的重要性。图文摘要