HIGH-RESOLUTION AUTORADIOGRAPHY

TLDR

The study describes methods for achieving high‑resolution autoradiography, emphasizing electron‑microscopic techniques and control experiments to determine optimal conditions. High‑resolution autoradiography is performed by applying a gelled film of monolayer silver halide crystals to specimens, storing the preparations with a drying agent at room temperature or refrigeration, developing the film in Microdol or a fine‑grain developer, and staining sections with uranyl or lead for electron‑microscopic examination. The experiments identified Ilford L‑4 emulsion with sub‑0.1‑µm crystals, demonstrated that background can be eliminated simply, and showed that the methods provide subcellular label localization and reproducible grain counts.

Abstract

Methods used in obtaining high resolution in autoradiography, with special emphasis on the technique of electron microscopic autoradiography, are described, together with control experiments designed to establish the optimum conditions or procedures. On the basis of these experiments the emulsion selected was Ilford L-4, with a crystal size slightly larger than 0.1 micron. It is applied to the specimen in the form of a gelled film consisting of a monolayer of silver halide crystals. Background, when present, can be eradicated by a simple method. The preparations can be stored, in presence of a drying agent, at room temperature or in a refrigerator. Photographic development is done in Microdol, or in a special fine grain "physical" developer. For examination in the electron microscope the sections are stained with uranyl or lead stains. These methods give a good localization of the label, at the subcellular level, and good reproducibility in relative grain counts.