Abstract
The goal of specimen preparation for electron microscopy of biological tissues and cells is to preserve fine structure as close to their native state as possible. Cryofixation is now generally accepted as the best initial fixation step providing superior preservation of not only fine structure but also antigenicity essential for immunoelectron microscopy. Currently, high-pressure freezing followed by freeze-substitution is the most reliable method to obtain a high yield of vitreous (ice-crystal damage-free) freezing. The application of high-pressure (in the range of 2,100 bars) lowers the freezing point and reduces the rate of ice nucleation and ice crystal growth. It has also been reported that vitrification depth could reach several hundred micrometer under high-pressure. Such a deep vitrification enables us to apply the frozen specimens to not only conventional electron microscopy of resin embedded specimen but also electron microscopic tomography, freeze-fracture method, and cryo-electron microscopy of vitrous sections (CEMOVIS). This review describes the practical basis and advantages of high-pressure freezing technique for fine structural electron microscopy.
