HIGH RESOLUTION AUTORADIOGRAPHY WITH DRY MOUNTED, FREEZE-DRIED FROZEN SECTIONS COMPARATIVE STUDY OF SIX METHODS USING TWO DIFFUSIBLE COMPOUNDS H-ESTRADIOL AND H-MESOBILIRUBINOGEN

Abstract

Localization of two soluble compounds, 3H-estradiol in liver and uterus and 3H-mesobilirubinogen in liver, has been studied by six autoradiographic methods: (I) Frozen sections, freeze-dried, dry mounted on emulsion-coated slides; (II) Frozen sections thawed on emulsion-coated slides; (III) Frozen sections thawed on glass slides and dipped in liquid emulsion; (IV) Freeze-dried tissue, vapor-fixed, epoxy-embedded, sectioned, dipped in liquid emulsion; (V) Freeze-dried tissue, paraffin-embedded, sectioned, deparaffinized, dipped in liquid emulsion; and (VI) Formalin-fixed tissue, paraffin-embedded, sectioned, deparaffinized and dipped in liquid emulsion. Methods II-VI show varying degrees of diffusion, and in some cases loss of activity from tissue, when compared with results obtained by dry mounting of freeze-dried frozen sections. Autoradiograms prepared by dry mounting of 0.75-, and 1-µ thick sections, cut and dried below –60°C, have been found superior.