Frösch D, Westphal C
J Microsc. 1985 Feb;137(Pt 2):177-83. doi: 10.1111/j.1365-2818.1985.tb02575.x.
When biological materials are infiltrated by a water-soluble melamine resin and hardened, they become as hard as glass. This is a prerequisite for extreme thin-sectioning. In this paper, the structural information from unsupported transparent thin sections of beef liver catalase, calf thymus DNA, horse spleen ferritin, insect muscle and rat microtubules is compared to that of normal thin sections. While ferritin molecules (12 nm diameter), microtubule subunits (8 nm long axis) and catalase crystals (8 nm subunit diameter) appear to become mechanically damaged in a 10 nm section (as measured by resectioning), DNA-molecules (3 nm diameter) are satisfactorily preserved during sectioning. Remarkably, for electron phase contrast imaging of unstained cross-sectioned insect muscle, a minimum section thickness of about 30-40 nm is required.
当生物材料被水溶性三聚氰胺树脂浸润并硬化后，它们会变得像玻璃一样坚硬。这是进行超薄切片的一个先决条件。在本文中，将来自牛肉肝过氧化氢酶、小牛胸腺DNA、马脾铁蛋白、昆虫肌肉和大鼠微管的无支撑透明薄片的结构信息与正常薄片的结构信息进行了比较。虽然铁蛋白分子（直径12纳米）、微管亚基（长轴8纳米）和过氧化氢酶晶体（亚基直径8纳米）在10纳米切片中似乎受到了机械损伤（通过再次切片测量），但DNA分子（直径3纳米）在切片过程中得到了良好的保存。值得注意的是，对于未染色的昆虫肌肉横截面的电子相衬成像，所需的最小切片厚度约为30 - 40纳米。
