MEDICO-BIOLOGIC RESEARCH 



A B 



Fig. 22. Magnified macroradiographs of A — bone section fixed (neutral formalin), and B — bone sec- 

 tion immersed into osmium fixative (see text) for 12 hours. The lack of calcium in osmium fixed bone is 

 quite obvious. 



The range of OM, methods of impregnation 

 and the selective absorption of OM by dif- 

 ferent elements of biological tissues, healthy 

 and diseased, these are only a few of the 

 many problems which will confront the re- 

 searcher. The change of behavior of cellular 

 elements during neoplastic diseases appears 

 to be one of the most promising fields as well 

 as the study of degenerated nerve fibers. The 

 further elaboration of methods is necessary 

 which permit the comparative study of 

 microradiograph and its colored replica. 

 Stain historadiography is such a method. It 

 has proven its validity in research on cal- 

 careous tissues. However, it is necessary to 

 find a similar method also for other tissues 

 low in absorbing x-rays. Ward's bio-plastic 

 cannot be used as embedding mediimi in this 

 case because it is too hard and cannot be cut 

 with the usual microtome. It is therefore 

 necessary to find some other embedding 

 agent which (1) does not produce any image 

 if radiographed, (2) is not too hard and (3) 

 at the same time does not prevent any 

 coloring with histological dyes. Coloring can 

 be done also after the disembedding of 

 radiographed sections but in this case there 



will be some structural dissimilarity between 

 embedded and disembedded sections. All 

 these and other problems of technique have 

 to be solved. 



When starting to make use of microra- 

 diography one has first of all to be clear 

 that the working magnification will be 

 120X-150X and only in rare cases 300X. 

 Consequently there is no sense in trying to 

 "squeeze out" of a microradiograph those 

 details which can only be seen with a higher 

 power. Comparative study of the colored and 

 the microradiographed specimen will be of 

 help in case the higher power is necessary 

 because the colored specimen has the same 

 limits of magnification as a histological slide. 



Further research is necessarj'- in micro- 

 radiography of tissues per se which are low 

 in absorbing x-rays. Here, first of all, the 

 simplification of equipment and technique is 

 necessary. The expensive and complicated 

 equipment cannot be recommended to 

 anatomy and histology laboratories espe- 

 cially if it requires a trained technical 

 staff for its exploitation. A new, possibly 

 grainless, emulsion is also one of the de- 

 mands of microradiography of tissues low in 



619 



