Kawasaki Yuto, Hosoyamada Yasue, Miyaki Takayuki, Yamaguchi Junji, Kakuta Soichiro, Sakai Tatsuo, Ichimura Koichiro
Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan.
Department of Nutrition, Faculty of Health Care Sciences, Chiba Prefectural University of Health Sciences, Chiba, Japan.
Front Cell Dev Biol. 2021 Mar 11;9:653472. doi: 10.3389/fcell.2021.653472. eCollection 2021.
Focused-ion beam-scanning electron microscopic (FIB-SEM) tomography enables easier acquisition of a series of ultrastructural, sectional images directly from resin-embedded biological samples. In this study, to clarify the three-dimensional (3D) architecture of glomerular endothelial cells (GEnCs) in adult rats, we manually extracted GEnCs from serial FIB-SEM images and reconstructed them on an Amira reconstruction software. The luminal and basal surface structures were clearly visualized in the reconstructed GEnCs, although only the luminal surface structures could be observed by conventional SEM. The luminal surface visualized via the reconstructed GEnCs was quite similar to that observed through conventional SEM, indicating that 3D reconstruction could be performed with high accuracy. Thus, we successfully described the 3D architecture of normal GEnCs in adult rats more clearly and precisely than ever before. The GEnCs were found to consist of three major subcellular compartments, namely, the cell body, cytoplasmic ridges, and sieve plates, in addition to two associated subcellular compartments, namely, the globular protrusions and reticular porous structures. Furthermore, most individual GEnCs made up a "seamless" tubular shape, and some of them formed an autocellular junction to make up a tubular shape. FIB-SEM tomography with reconstruction is a powerful approach to better understand the 3D architecture of GEnCs. Moreover, the morphological information revealed in this study will be valuable for the 3D pathologic evaluation of GEnCs in animal and human glomerular diseases and the structural analysis of developmental processes in the glomerular capillary system.
聚焦离子束扫描电子显微镜断层扫描（FIB-SEM）能够更轻松地直接从树脂包埋的生物样本中获取一系列超微结构的断层图像。在本研究中，为了阐明成年大鼠肾小球内皮细胞（GEnC）的三维（3D）结构，我们从连续的FIB-SEM图像中手动提取GEnC，并在Amira重建软件上对其进行重建。在重建的GEnC中，管腔和基底表面结构清晰可见，而传统扫描电子显微镜只能观察到管腔表面结构。通过重建的GEnC可视化的管腔表面与通过传统扫描电子显微镜观察到的非常相似，表明可以高精度地进行三维重建。因此，我们成功地比以往任何时候都更清晰、精确地描述了成年大鼠正常GEnC的三维结构。发现GEnC由三个主要的亚细胞区室组成，即细胞体、细胞质嵴和筛板，此外还有两个相关的亚细胞区室，即球状突起和网状多孔结构。此外，大多数单个GEnC构成“无缝”管状形状，其中一些形成自细胞连接以构成管状形状。具有重建功能的FIB-SEM断层扫描是更好地理解GEnC三维结构的有力方法。此外，本研究中揭示的形态学信息对于动物和人类肾小球疾病中GEnC的三维病理学评估以及肾小球毛细血管系统发育过程的结构分析将具有重要价值。
