title: Prevention of negative chemography in phenylenediamine stained autoradiographs of plastic semithin sections.
abstract: Negative chemography is the loss of latent image during autoradiographic exposure, due to reactive groups in the specimen. Tissue fixed with glutaraldehyde and osmium tetroxide, block stained with p-phenylenediamine and embedded in Epon for light microscope sections causes intense negative chemography when autoradiographed by dipping in Ilford K2 emulsion: this cannot be completely prevented by separating section from emulsion by means of a layer of evaporated carbon. Chemical treatment of the sections before autoradiography may reduce the chemography. Treatment with 1% hydrogen peroxide for 15 min reduced it to such an extent that subsequent coating with 5 nm carbon abolished it. Material block stained in this way gave excellent contrast, both for light and electron microscopy.
mesh_terms: D000818:Animals; D001345:Autoradiography; D001980:Bronchi / Q000033:anatomy & histology; D002244:Carbon; D055598:Chemical Phenomena; D002621:Chemistry; D005188:False Negative Reactions; D005404:Fixatives; D006801:Humans; D006861:Hydrogen Peroxide; D007420:Intestine, Large / Q000033:anatomy & histology; D007421:Intestine, Small / Q000033:anatomy & histology; D008168:Lung / Q000033:anatomy & histology; D008297:Male; D051379:Mice; D009993:Osmium Tetroxide; D010655:Phenylenediamines; D013194:Staining and Labeling
chemical_list: D005404:Fixatives; D010655:Phenylenediamines; D002244:Carbon; D006861:Hydrogen Peroxide; D009993:Osmium Tetroxide; C029728:4-phenylenediamine