Electron Microscopical Studies of the Latent Image Obtained by Exposures to Alpha Particles, X-Rays, and Light

Abstract

The latent image of ordinary photographic emulsions has not been resolved. However, the slightly enlarged latent image as obtained by physical gold development can be demonstrated by means of the electron microscope. For the case of a fast negative emulsion it is shown that different types of exposures result in latent image centers of significantly different size distribution characteristics. High-intensity alpha-particle and x-ray exposures produce a very large number of finely dispersed centers; irradiation with light of optimum intensity and 1/100 sec duration forms a small number of centers; only very few specks result from exposures to light of very low intensity. The patterns observed are in line with expectations based on current photographic theory.

MacroMolecular Complexes

“…Tissue culture techniques (Hild, 1957;Peterson and Murray, 1955) should be of great operational value in connection with ultrarapid freezing because of the critical limitations imposed by the specimen size. Chemical and biochemical investigations (Folch et ah, 1958) of the myelin sheath and other lamellar systems will continue to provide the frame of reference for all research in this field, making full use of the specific advantages inherent in the new techniques for the study of enzymatic activity by electron microscopy ( Barrnett and Palade, 1959), high-resolution autoradiography (Fernandez- Moran, 1959d;Hoerlin and Hamm, 1953), and related cytochemical methods. With an integrated physiological, biochemical, and biophysical approach, we may thus hope to gain a better understanding of these Huid crystal elements which are the true "energy transducers of life."…”

Macromolecular Complexes

“…Low temperatures markedly reduce the fog and background without impairing the cumulative effects of the radioactivity processes on the silver halides. After exposures of the order of 2 to 8 weeks, the latent image centers are developed and enlarged at low temperatures by using gold thiocyanate ( Hoerlin and Hamm, 1953) solutions. Interpretation of the images obtained with this method is still highly tentative, since the possibility that we might be dealing with "autochemograms" and other spurious effects must first be conclusively ruled out.…”

“…Tissue culture techniques (Hild, 1957;Peterson and Murray, 1955) should be of great operational value in connection with ultrarapid freezing because of the critical limitations imposed by the specimen size. Chemical and biochemical investigations (Folch et ah, 1958) of the myelin sheath and other lamellar systems will continue to provide the frame of reference for all research in this field, making full use of the specific advantages inherent in the new techniques for the study of enzymatic activity by electron microscopy ( Barrnett and Palade, 1959), high-resolution autoradiography (Fernandez- Moran, 1959d;Hoerlin and Hamm, 1953), and related cytochemical methods. With an integrated physiological, biochemical, and biophysical approach, we may thus hope to gain a better understanding of these Huid crystal elements which are the true "energy transducers of life.…”