A SIMPLIFIED METHOD FOR OBTAINING 0.5-MU-M 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 reso lution. Small tissues are embedded in agarose so that they can be grou ped together and oriented for sectioning before infiltration with PEG 4000, a water-soluble polymer. Fixation, embedding, sectioning, and st aining can be performed in 1 day. Results from immunocytochemical stud ies localizing actin and tubulin on 0.5-mu m sections of PEG-embedded specimens are compared with those obtained on semi-thin sections of ar aldite-embedded specimens and demonstrate the ease, speed, and increas ed sensitivity of this embedding method.