RESOLUTION IN AUTORADIOGRAPHY USING SEMITHIN SECTIONS

Abstract
Resolution studies were performed on light microscope autoradiographic specimens of 0.5-1 µ thicknesses coated with Ilford L4 and Kodak NTB2 and AR10 emulsions. A radioactive line source, previously employed for electron microscope autoradiography (Salpeter, Bachmann and Salpeter, 1969; Salpeter and Salpeter, 1971), was used. It was found that with tritium labeling the half-distance (HD) was approximately 3500 Å. This value was not significantly altered with increasing section beyond 0.5 µ or emulsion thickness beyond ~2,000 Å. A 0.5-µ section labeled with 14C had an HD value of 7000 Å when coated with a monolayer of Ilford L4 or Kodak NTB2 emulsion. Increasing section or emulsion thickness did increase this value. It was found that the density distributions, normalized in units of their own HD, gave a good fit to the set of universal curves derived from electron microscope autoradiographic specimens. These universal curves are thus applicable for analyzing light microscope autoradiographic specimens. Some tritium HD values applicable to high voltage microscopy are also given.

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