182 Silver Impregnation I (chap. 14) 



11. Rinse in distilled water. 



12. Fix in 5% sodium thiosulfate (5 gm./lOO ml. water): 3 minutes. 



13. Wash in running water: 5 minutes. 



14. Counterstain if desired. 



15. Dehydrate, clear, and mount. 



results: 



reticulum fibers — black 



other tissue elements — depends on counterstain 



comments: 



Grid ley uses periodic acid for oxidation in preference to potassium 

 permanganate and oxalic acid because the latter combination fre- 

 quently causes the sections to detach from the slides. 



Laidlow's Method (1929) 



fixation: Bouin's recommended. Formalin-fixed can be Bouinized 3 

 days to produce almost Bouin's results. 



solutions: 



Ammoniacal silver carbonate solution: 



In a clean 125 or 250 ml. glass-toppered graduate, dissolve 6 gm. of 

 silver nitrate in 10 ml. distilled water. Add 1 15 ml. saturated solution 

 of lithium carbonate in distilled water. Shake well. Settle precipitate 

 and pour off solution to leave about 35 ml. of precipitate. Wash well 

 with distilled water 4 or 5 times. Allow to settle, pour off wash water 

 and gradually add ammonia, shaking occasionally until fluid is almost 

 clear. A few grains of precipitate should remain. Add distilled water 

 to a total of 60 ml. Shake and filter into brown stock bottle. Keeps for 

 several months. 



Gold chloride: 



gold chloride stock solution, 1% (1 gm./lOO ml. 



water) 10.0 ml. 



distilled water 40.0 ml. 



procedure: 



1. Deparaffinize and hydrate slides to water; remove HgCl2 if pres- 

 ent. 



2. Oxidize in potassium permanganate, 0.25% (0.25 gm./lOO ml. 

 ^vater): 3 minutes. 



3. Wash in running water: 3 minutes. 



