Resolution for 125I-labeled specimens under electron microscope (EM) autoradiographic conditions was assessed experimentally. With this isotope the size of the silver halide crystal was the most important resolution-limiting factor. Heavy metal staining such as is routinely used in preparing animal tissues for EM autoradiography produced an improvement in resolution of approximately 15-20%. For a 500-1,000-A biological tissue section fixed with OsO4 and stained with uranyl acetate, we obtained resolution (half distance, HD) values of approximately 800 +/- 120 A using Ilford L4 emulsion and 500 +/- 70 A using a Kodak NTE-type emulsion. General aspects of resolution-limiting factors and comparison with 3H and 14C values are discussed.
Resolution in electron microscope autoradiography. III. Iodine-125, the effect of heavy metal staining, and a reassessment of critical parameters.
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M M Salpeter, H C Fertuck, E E Salpeter; Resolution in electron microscope autoradiography. III. Iodine-125, the effect of heavy metal staining, and a reassessment of critical parameters.. J Cell Biol 1 January 1977; 72 (1): 161–173. doi: https://doi.org/10.1083/jcb.72.1.161
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