The use of specific antibody in electron microscopy. III. Localization of antigens by the use of unmodified antibody.

Antibody staining was observed in the electron microscope by means of untagged antibody and osmium fixation. The antibody was visualized as a change in morphology due to its deposition on the antigenic structures. Glycerinated chicken breast muscle was stained with antimyosin, anti-H-meromyosin, and antiactin. The staining patterns obtained by electron microscopy were consistent with those previously demonstrated by fluorescence microscopy. A second method was used for confirmation of antibody staining. This consisted of extraction of unstained portions of the sarcomere with 0.6 M potassium iodide, 10(-4)M adenosine triphosphate solution. Stained regions of the sarcomere remained intact because of insolubility of the combined antigen and antibody.