HPF (High Pressure Freezing System) allows bringing biological samples into a vitrified state by ultra-rapid freezing under high pressure (~ 2100 bars). The samples must be under 200 µm thick and 1.5 mm in diameter. Following HPF the samples are usually freeze-substituted and resin embedded at low temperature.
This system is used for preparing biological samples for transmission electron microscopy. It is best suited for very young tissues (e.g. root tips, developing seeds,…).