The high pressure freezer (HPF) in the NIC, a Bal-Tec HPM 010, is useful in the cryopreparation of biological samples for electron microscopy (EM). In order to maintain excellent structure in tissues for EM, the HPF freezes the sample at very low temperature using liquid nitrogen applied to the sample holder at high pressure. The combination of extreme cold and high pressure causes water in the sample to become viscous, which minimizes nucleation of water crystals. Formation of water crystals can damage cellular structures, causing artefacts when observing at high magnification. Therefore, the HPF is superior to other types of cryopreparation for samples intended for subsequent freeze drying and SEM or TEM investigations.