A simple procedure for the destaining of stripping-film autoradiographs.

Trypsin digestion of stripping-film radioautographs after photographic processing and staining removes the excess gelatin without affecting the intensity of the radioautograph, and results in a thin colorless emulsion that makes microscopic observation and photography easier. Methanol-fixed smears or Carnoy-fixed tissue sections, labeled with tritiated thymidine and unstained, were radioautographed, and the radioautographs were developed, fixed, stained with hematoxylin, and counterstained with eosin. The slides were air-dried, rehydrated for 10 min in distilled water, and incubated in a 0.01% solution of trypsin at 37 °C for 6-8 min. In stripping-film radioautographs digested as described, the 10 mu supporting layer of gelatin is completely removed, but the sensitized layer containing the developed silver grains is not affected.