MICROWAVES AND HEAT IN ALDEHYDE FIXATION - MODEL EXPERIMENTS WITH BOVINE SERUM-ALBUMIN

Most model experiments concerning tissue fixation have used low concen trations of fixatives and proteins. Here, high concentrations (up to 3 2%) of bovine serum albumin (BSA) were reacted with formaldehyde (1-20 %) and glutaraldehyde (0.5-4%). Gels were formed between 16% BSA and 1 0-20% formaldehyde at room temperature, but not with percentages of fo rmaldehyde lower than 4%. Microwave application or heating in a water bath to 50 degrees C gave a gel from 1 to 20% formaldehyde. Sixteen pe rcent BSA also gave a gel with glutaraldehyde from 0.5 to 4%. Cone and plate viscometry showed rapidly increasing viscosity at 4% formaldehy de and 16% BSA at room temperature. At 50 degrees C, gels formed at a low concentration of formaldehyde. Tissue fixation in which the local concentrations of protein may be in excess of 30% is probably more com plete than in vitro experiments in which low concentrations of reagent s have been used to permit subsequent spectrometry. This was confirmed by polyacrylamide gel electrophoresis of liver, (C) 1998 Academic Pre ss.