Factors which Influence the Latent Image in Autoradiography

Abstract

Sections treated with N-ethyl-maleim'ide, a sulfhydryl blocking reagent, exhibit similar grain counts over nonradioactive and S-labeled tissues. This reveals that no chemo-graphic effects were produced by sulfhydryl groups in tissues fixed and prepared in the manner described. It was noted, however, that background count over tissue sections is consistently tower than over adjacent him, indicating perhaps the existence of substances in tissues which interfere with the production of the latent image. These effects have been eliminated by coating the tissues with celloidin. Celloidin coating can be used for most emitters including S but not for tritium. A special method for tritium, not involving celloidin coating is given.