200 Silver Impregnation II (chap. 15) 



B. potassium dichromate, 5% aqueous 65.0 ml. 



glacial acetic acid 6.0 ml. 



Mix A and B. 



Remove tissues from any of above fluids, blot and place immediately 

 in silver solution: 18-24 hours. Proceed into step number 2 above 

 (under Staining). 



Moliner's Modification {1957) 



fixation: fix 3-5 mm. pieces, 3 days, change daily. 



potassium dichromate, 6% aqueous 40.0 ml. 



potassium chlorate, 5% aqueous 20.0 ml. 



chloral hydrate, 20% aqueous 30.0 ml. 



formalin 10.0 ml. 



staining: 



1. Transfer tissue blocks to 3% aqueous potassium dichromate: 3 

 days, change twice a day. 



2. Transfer to 1% aqtieous silver nitrate (Igm./lOO ml. water): 3 

 days, room temperature. 



SECTIONING AND MOUNTING: 



1. CiU frozen sections, 50-100 microns. Sections can be kept in abso- 

 lute alcohol until mounted. 



2. Mount on slides and clear. Synthetic mountants can be used with 

 a cover glass. (Before synthetic moiuitants were developed, Golgi 

 preparations had to be mounted in balsam withoiu a cover glass.) 



Ramon y Cajal's Pyridine-Silver Method (modified by davenport et 

 al, 1934) B 



fixation: as soon as possible in: 



absolute ethyl alcohol 98.0 ml. 



ammonia, concentrated 2.0 ml. 



Fix for 1-6 days, preferably no longer. 



procedure: 



1. Treat tissue blocks in 5% aqueous pyridine: 24 hours. This is 

 recommended; but Davenport et al. say it can be optional. 



2. Wash in distilled water: 2-6 hours; change every half hour. 



3. Impregnate in 1.5-2.0% aqueous silver nitrate (1.5-2.0 gm./lOO 

 ml. water), 37°C: 2 to 3 days, or longer depending on size of tissue 

 blocks. A minimum time yields the best differentiated tissue. The 



