High-Pressure Freezing for Preservation of High Resolution Fine Structure and Antigenicity for Immunolabeling

What is high-pressure freezing (HPF)? HPF is a method of specimen preparation for electron microscopy (EM) that freezes noncryoprotected samples up to 0.5 mm in thickness without significant ice crystal damage. Other freezing methods are limited to 1/100 (plunge and impact freezing) to 1/10 (propane jet freezing) that sample thickness. With HPF you are working in the realm of whole cells and tissues instead of small cells or cell cortical regions. For more details on the theory of how HPF works, and some examples of its application, there are several reviews available (1 -4 ).