AUTORADIOGRAPHY 341 



as aggregates, as shown by the sunbursts, and as dispersed atoms or mol- 

 ecules, as shown by the individual alpha tracks. It is also obvious that 

 the aggregated polonium was selectively and almost completely removed 

 from the blood in about 2 hr. The autoradiograms were made by apposi- 

 tion of a dried blood smear with alpha-track emulsion (NTA). 



As discussed in Chap. 8, autoradiography has been of great value when 

 used in conjunction with paper chromatography. With these combined 













> 





lo, (6) 



Fig. 7-5. (a) Autoradiograin of rat blood at 2 to lU niin after intravenous administra- 

 tion of polonium chloride. Note sunbursts A, which indicate presence of aggregates. 

 (6) Autoradiogram at 2 to 24 hr after administration. Note presence of individual 

 alpha tracks only. {From John C. Gallimore, Jr., A Radiochemical and Autoradio- 

 graphic Study of the Distribution of Polonium in Rats after Intravenous Administration, 

 University of Rochester Atomic Energy Project Report UR-220, 1952.) 



techniques it becomes a simple matter to identify various labeled com- 

 pounds and also to establish the purity of a particular labeled compound 

 before its use in an experiment. This may be of particular importance in 

 the testing of C^^-labeled organic compounds to determine whether or not 

 significant radiation decomposition has occurred. A classical example of 

 the procedure is the work of Taurog, Chaikoff, and Tong (37), who iden- 

 tified the organic iodine of the plasma as thyroxine. Figure 7-6a shows 

 the position taken by thyroxine added to the butanol extract of plasma 

 from rats given P'", as determined by spraying with diazotized sulfanilic 

 acid. Figure 1-Qh is the autoradiogram of the filter-paper strip, and the 

 correspondence in position and shape leaves little question as to the iden- 

 tity of the P^ ^-labeled material with the added thyroxine. 



