A simplified method for obtaining 0.5-microns sections of small tissue specimens embedded in PEG.

We describe a new method for embedding small specimens in polyethylene glycol (PEG) 4000. This method preserves cell morphology and provides sensitive immunocytochemical labeling with excellent subcellular resolution. Small tissues are embedded in agarose so that they can be grouped together and oriented for sectioning before infiltration with PEG 4000, a water-soluble polymer. Fixation, embedding, sectioning, and staining can be performed in 1 day. Results from immunocytochemical studies localizing actin and tubulin on 0.5-micron sections of PEG-embedded specimens are compared with those obtained on semi-thin sections of araldite-embedded specimens and demonstrate the ease, speed, and increased sensitivity of this embedding method.