Pericellular End-Bulbs {or Bouions) 207 



Nauta and Gygax Method (1951) B 

 fixation: 10% formalin: 2 weeks to 6 months. 

 sectioning: frozen sections, 15-20 microns. 



solutions: 



Silver solution A: 



silver nitrate 1-5 gm. 



distilled water 100.0 ml. 



pyridine 5.0 ml. 



Silver solution B (ammonia ted silver): 



Dissolve 0.45 om. silver nitrate in 20.0 ml. distilled water. Add 10.0 

 ml. of 95% ethyl alcohol. From calibrated pipettes add 2.0 ml. am- 

 monia (concentrated) and 2.2 ml. of 2.5% sodium hydroxide. Mix 

 thoroughly and keep the container covered to prevent escape of am- 

 monia. 



Reducing solution: 



10% ethyl alcohol 45.0 ml. 



10% formalin 2.0 ml. 



1% citric acid 1.5 ml. 



procedure: 



1. Demyelinate sections in 50% ethyl alcohol plus 1.0 ml. ammonia 

 per 100 ml.: 6-12 hours. A longer time has no ill effect. 



2. Wash in distilled water, 3 changes: few seconds each. 



3. Impregnate in silver solution A: 12-24 hours. 



4. \V'\x\\ no washino, transfer into silver solution B: 2-5 minutes. 



5. Transfer directly into reducing solution tmtil the sections tmn 

 gold in color. 



6. Transfer to 2.5% sodium thiosulfate (2.5 gm./lOO ml. water): 1-2 

 minutes. 



7. Wash in distilled water, at least 3 changes. 



8. Dehydrate rapidly, clear, and motmt, 



results: 



nerve fibers and endings — black 

 cells — pale yellowish brown 



comments: 



This method is nonselective and stains normal as well as degenerat- 

 ing axons. For degenerating axons see following methods. 



