CHAPTER 7 



AUTORADIOGRAPHY 



General CoNSiDERATiONS-Laboratory Requirements; Photographic Emulsions; 

 Properties of the Radioisotope; Dosage of Isotope and Exposure Time; Handhng of 

 Tissues Specific Techniques— Simple Apposition; Mounting Method; Coating 

 Method- Stripping-film Method. Applications— Chemical; Anatomical Relation- 

 ships- Metabolic: Translocation; Bone grouch and development; Cellular biosynthesis; 

 Embryonic development; Dysfunction; Quantitative Aspects; Track and gram counting. 

 Interpretation. 



Ionizing radiations act upon the photographic emulsion in the same 

 manner as light does. If a piece of film is exposed to an object containing 

 radioactive material, a photographic image is produced upon develop- 

 ment which provides visuahzation of the location of the radioactivity in 

 the sample. This image is known by such terms as autoradiogram, auto- 

 radiograph, autogram, and radioautogram. General references (4, 9, 10) 

 may be consulted for historical aspects which date back to the observa- 

 tions of Becquerel in 1895 on the fogging of a photographic plate by 



uranium ore. 



On the gross scale, autoradiography is of particular advantage with 

 heterogeneous samples in providing information that is unobtainable by 

 counting methods. But perhaps of greatest import from the biological 

 standpoint is the fact that the autoradiographic technique permits study 

 of cellular function at the cell level. It becomes possible to develop cor- 

 relations between cytological structure, cellular physiology and pathol- 

 ogy, physicochemical properties of the cells, and the location pattern of 

 specific chemical elements introduced into the system. 



The same requirements for interpretation as discussed in Chap. 2 for 

 general radioisotope usage must be taken into account, namely, chemical 

 effects radiochemical contamination, radiation effects, exchange reac- 

 tions, knd isotope effects. In addition, there is always the possibihty of 

 artifacts which must be guarded against by careful technique, control 

 experiments, and reserve in the interpretation of the autoradiogram. 

 There seems little question, however, that the tedium of precautionary 

 measures, which decreases with experience and use of standardized proce- 

 dures, is far overbalanced by the information made available. 



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