The BioPulverizer reduces tissue hard-frozen in liquid nitrogen to a fine powder. Because of the high water content, most fresh tissue becomes as brittle as glass at liquid nitrogen temperatures. A sharp blow with a hammer will shatter it into tiny pieces. Called freeze-fracturing or cryopulverization, the method is especially useful for preparing tough, fibrous tissues such as skin, cartilage, cornea, etc. for subsequent rapid cell disruption using other techniques. The Bio-Pulverizer consists of a hole machined in a stainless steel base into which fits a special piston, or pestle. In a typical procedure, up to 10 g of animal or plant tissue is hard-frozen in liquid nitrogen and placed in the pre-chilled BioPulverizer. The piston delivers a blow to the brittle tissue reducing it to powder. Freeze fracturing with the Bio-Pulverizer is also useful for extracting labile tissue metabolites.