Abstract
A previous report( 1 ) described a method for preparation of radioautographs of animal tissues without isotope loss.∗ This work demonstrated the ease of extraction of P32 from frozen-dried liver sections when they come into contact with water. This result agrees with chemical studies of P32 distribution in tissues which have shown that a major part of the P32 should be present in water soluble form( 2 ). The present report describes results obtained when frozen-dehydrated tissue sections containing radioisotopes are exposed to extraction by a variety of reagents, both aqueous and nonaqueous. Radioautographic exposures were made with the extracted tissue sections and also with non-extracted control sections, as will be described. The results were evaluated by comparing the photographic densities and pattern of localization of radioautographs obtained from analogous tissue sections subjected to various types of extraction with those of the control sections. It is an application of the radio-autographic method to obtain information about the chemical nature of radioisotopes distributed in tissues.
Solubility studies have been of very limited value in conventional technic histo-chemistry as Gain( 3 ) has pointed out in a recent critical discussion. Tissues prepared by quick-freezing and drying warrant further investigation from this standpoint; however, certain limitations are inherent in all solubility studies( 3 ). An advantage of the quick-freezing and freezing-drying process for preparing tissues consists of minimal alterations in chemical and biological characteristics of the system( 4 ). Due to the porous solid framework that is formed, the solubility of compounds in such preparations is extremely rapid and complete, as was illustrated by Flosdorf( 4 ) in the case of gelatin. When a thin (5 to 8 μ) frozen-dehydrated tissue section is treated with various solvents, the conditions for rapid extraction of the tissue should be optimal.
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