COMPARATIVE HISTOCHEMISTRY 



OF NEURONS DIFFERING 



IN THEIR FUNCTION 



G. ROSKIN 



1. Each type of neurons differs according to its physiological characte- 

 ristic not only in structure, but in chemical composition as well. Thus, 

 as it is impossible to give full characteristics of neuron types by means 

 of a fuUy structural description, they should be supplemented with cyto- 

 chemical data. 



2. In a number of neurons cytochemical divergences are so great 

 that they can be revealed with sufficient certitude by modem histoche- 

 mical methods. 



This fact was proved by a comparison of cytochemical reactions in 

 sensory neurons of spinal ganglia with those in motor neurons of spinal 

 cord, the foUowing components of the cyto- and karyoplasm of the above 

 cells having been investigated. 



1. Amino acids (arginine, histidine, triptophane). 



2. Basic and acid proteins; histones. 



3. Nucleic acids (DNA and RNA) and nucleotides. 



4. Glycogen and glycoproteids. 



5. Lipids. 



6. Plasmal. 



7. Glutathione and SH-groupes. 



8. Alkaline and acid phosphotases. 



9. Dehydrase and succinodehydrase. 



3. Each type of neurons cannot be characterised by any single compo- 

 nent of protoplasm enumerated above, but by a regular complex of chemi- 

 cal and biochemical properties. 



4. Différences between various types of neurons are limited not only 

 by those of chemical and biochemical nature. Together with qualitative and 

 quantitative distinctions a topographie distribution of protoplasmic com- 

 ponents is of great importance. Thus, the types of neurons differ from each 

 other not only cytochemically, but also in their cytotopochemical charac- 

 ters. 



5. In diverse types of neurons ribonucleic acid may be in a variously 

 strong bond with the proteins of protoplasm and nucleolei. 



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