A simplified method of "hypothetical grain" analysis of electron microscope autoradiographs

An improved method for the analysis of high resolution electron microscope autoradiographs is described which is simple and quick to perform. The method uses a transparent screen superimposed over the autoradiograph prints to provide information on the distribution of grains over neighboring structures, produced by radioactive disintegrations occurring in different regions of the section. This "cross-scatter" information is used to estimate the radioactivity in different structures without the need to make any assumptions about the size, shape and arrangement of the structures within the autoradiographs being analyzed. The method allows activity in membranes and other linear structures to be determined and also the accuracy attributable to the activity values obtained.