Richter K
University of Lausanne, Switzerland.
Scanning Microsc Suppl. 1996;10:375-85; discussion 385-6.
Cryoelectron microscopy allows the observation of hydrated samples at high spatial resolution, and it would be of great interest in biology to apply this method to cells and tissues. However, because of technical problems, the cryo-observation of frozen hydrated ultrathin sections of bulk material has not become an established method. The major limitations are due to the difficulty of achieving the vitrification of such material, and the structural deformation caused by ultrathin sectioning: 1. The vitrification of cells in a physiological environment requires high-pressure freezing. However, new results suggest that the pressure may alter the ultrastructure of the sample. 2. Cryosectioning compresses structures in the cutting direction about 40%. This deformation does not necessarily destroy the character of macromolecular assemblies, but since it depends on the properties of the material, internal standards cannot be used to correct for the deformation of all the structures in a cell.
冷冻电子显微镜能够在高空间分辨率下观察水合样本，将该方法应用于细胞和组织在生物学领域会非常有意义。然而，由于技术问题，对大块材料的冷冻水合超薄切片进行冷冻观察尚未成为一种成熟的方法。主要限制在于实现此类材料玻璃化的困难，以及超薄切片造成的结构变形：1. 在生理环境中使细胞玻璃化需要高压冷冻。然而，新的结果表明压力可能会改变样本的超微结构。2. 冷冻切片会使切割方向的结构压缩约40%。这种变形不一定会破坏大分子组装体的特征，但由于它取决于材料的特性，因此不能使用内部标准来校正细胞中所有结构的变形。
