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RADIOACTIVITY; BIOLOGICAL TRACERS 



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M- f 



(a) 



(b) 



Figure 5-2. Microradiography. (a) 



X-ray microradiograph (5 kvp) of a sec- 

 tion of natural compact bone (tibia). 

 Note the large (black) osteonic canals 

 and the (light) mineralized regions. 

 Magnification 500 x. (b) Alpharadio- 

 graph (source 2 mc/cm 2 of Po 210 ) of a 

 section of the same bone demineralized. 

 Note regions of low-density (dark) and 

 high-density (light) organic material. 

 Magnification 150x. Together (a) and 

 (b) demonstrate directly the regions of 

 growth of young bone around the 

 osteonic canal: tissue mostly organic, 

 only lightly mineralized. (c) Alpha- 

 radiograph showing filiform papillae 

 (top) of the human tongue. Note the 

 dense fibrous collagen core of the 

 papillae and of the supporting base of 

 the epithelium, and observe the low- 

 density (black) mucous-forming cells at 

 the bottom of the picture. (Courtesy of 

 L. F. Belanger, University of Ottawa 

 Medical Faculty, and D. H. Copp, 

 University of British Columbia Medical 

 School.) 



