Light and Electron Microscopic Localization of Antigens in Tissues Embedded in Polyethylene Glycol With a Peroxidase-Labeled Antibody Method

Tissues embedded in polyethylene glycol (PEG) were used for the immunocytochemical localization of cellular antigens at the light and electron microscopic level. For demonstration of the method, growth hormone and luteinizing hormone were localized in the anterior pituitary gland of the rat embedded in PEG, using peroxidase-labeled antibodies. PEG is water-soluble, has a low melting temperature yet is firm enough to be sectioned at room temperature. Preservation of cellular ultrastructure is good. The use of PEG-embedded tissue permits precise correlation of light and electron microscopic observations of the same tissue section.