Tanaka K, Mitsushima A, Kashima Y, Nakadera T, Osatake H
Department of Anatomy, Tottori University School of Medicine, Yonago, Japan.
J Electron Microsc Tech. 1989 Jun;12(2):146-54. doi: 10.1002/jemt.1060120208.
In 1985 we developed an ultrahigh-resolution scanning electron microscope with a resolution of 0.5 nm. It is equipped with a field emission gun and an objective lens with a very short focal length. In this study we report a survey of some different preparation techniques and biological specimens using the new scanning electron microscope. Intracellular structures such as cell organelles were observed surprisingly sharper than those observed by ordinary scanning electron microscopes. However, at magnifications over 250,000 x, platinum particles could be discerned as scattered pebbles on the surface of all structures in coated materials. Using an uncoated but conductively stained specimen, we successfully observed ribosomes on a rough endoplasmic reticulum at a direct magnification of 1 million. In these images some protrusions were recognized on the ribosomes. Ferritin and immunoglobulin G were used as samples of biological macromolecules. These samples were observed without metal coating and conductive staining. The ferritin particles appeared as rounded bodies without any substructure on the surface and immunoglobulin G as complexes of three-unit bodies. In the latter the central body might correspond to the Fc fragment and two side ones to Fab fragments. We assume that ultrahigh-resolution scanning electron microscopy is an effective means for observation of the cell fine structures and biological macromolecules. It will open a new research field in biomedicine.
1985年，我们研制出了一台分辨率为0.5纳米的超高分辨率扫描电子显微镜。它配备了场发射枪和焦距极短的物镜。在本研究中，我们报告了使用这台新型扫描电子显微镜对一些不同制备技术和生物标本的调查情况。细胞内结构，如细胞器，其观察效果比普通扫描电子显微镜观察到的要清晰得多。然而，在放大倍数超过250,000倍时，铂颗粒在镀膜材料中所有结构的表面上可被视为散落的小石子。使用未镀膜但经过导电染色的标本，我们成功地在直接放大倍数为100万倍的情况下观察到了粗面内质网上的核糖体。在这些图像中，核糖体上可识别出一些突起。铁蛋白和免疫球蛋白G被用作生物大分子样本。这些样本未进行金属镀膜和导电染色就被观察了。铁蛋白颗粒呈现为表面没有任何亚结构的圆形物体，免疫球蛋白G呈现为三单元体的复合物。在后者中，中央体可能对应于Fc片段，两个侧体对应于Fab片段。我们认为超高分辨率扫描电子显微镜是观察细胞精细结构和生物大分子的有效手段。它将在生物医学领域开辟一个新的研究领域。
