Trebichalská Zuzana, Javůrek Jakub, Tatíčková Martina, Kyjovská Drahomíra, Kloudová Soňa, Otevřel Pavel, Hampl Aleš, Holubcová Zuzana
Department of Histology and Embryology, Faculty of Medicine, Masaryk University, Brno, Czechia.
TESCAN ORSAY HOLDING, a.s., Brno, Czechia.
Front Cell Dev Biol. 2021 Nov 2;9:755740. doi: 10.3389/fcell.2021.755740. eCollection 2021.
The egg plays a pivotal role in the reproduction of our species. Nevertheless, its fundamental biology remains elusive. Transmission electron microscopy is traditionally used to inspect the ultrastructure of female gametes. However, two-dimensional micrographs contain only fragmentary information about the spatial organization of the complex oocyte cytoplasm. Here, we employed the Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) to explore human oocyte intracellular morphology in three dimensions (3D). Volume reconstruction of generated image stacks provided an unprecedented view of ooplasmic architecture. Organelle distribution patterns observed in nine donor oocytes, representing three maturational stages, documented structural changes underlying the process by which the egg acquires developmental competence. 3D image segmentation was performed to extract information about distinct organelle populations, and the following quantitative analysis revealed that the mitochondrion occupies ∼ 4.26% of the maturing oocyte cytoplasm. In summary, this proof-of-concept study demonstrates the potential of large volume electron microscopy to study rare samples of delicate female gametes and paves the way for applying the FIB-SEM technique in human oocyte research.
卵子在我们物种的繁殖中起着关键作用。然而，其基本生物学特性仍然难以捉摸。传统上，透射电子显微镜用于检查雌性配子的超微结构。然而，二维显微照片仅包含有关复杂卵母细胞细胞质空间组织的零碎信息。在这里，我们采用聚焦离子束扫描电子显微镜（FIB-SEM）来三维（3D）探索人类卵母细胞的细胞内形态。生成的图像堆栈的体积重建提供了卵质结构前所未有的视图。在代表三个成熟阶段的九个供体卵母细胞中观察到的细胞器分布模式，记录了卵子获得发育能力过程中的结构变化。进行3D图像分割以提取有关不同细胞器群体的信息，随后的定量分析表明，线粒体占成熟卵母细胞细胞质的约4.26%。总之，这项概念验证研究证明了大体积电子显微镜在研究脆弱雌性配子稀有样本方面的潜力，并为在人类卵母细胞研究中应用FIB-SEM技术铺平了道路。
