Application of microwave technology to the processing and immunolabeling of plastic-embedded and cryosections

We have adapted existing microwave irradiation (MWI) protocols and applied them to the processing and immunoelectron microscopy of both plastic-embedd ed and frozen sections. Rat livers were fixed by rapid MW irradiation in a mild fixation solution. Fixed liver tissue was either cryosectioned or dehy drated and embedded in Spurr's, Unicryl, or LR White resin. Frozen sections and sections of acrylic-embedded tissue were immunolabeled in the MW oven with an anti-catalase antibody, followed by gold labeling. Controls were pr ocessed conventionally at room temperature (RT). The use of MWI greatly sho rtened the fixation, processing, and immunolabeling times without compromis ing the quality of ultrastructural preservation and the specificity of labe ling. The higher immunogold labeling intensity was achieved after a 15-min incubation of primary antibody and gold markers under discontinued MWI at 3 7C. quantification of the immunolabeling for catalase indicated a density i ncrease of up to fourfold in the sections immunolabeled in the MW oven over that of samples immunolabeled at RT. These studies define the general cond itions of fixation and immunolabeling for both acrylic resin-embedded mater ial and frozen sections.