SECTION TWO 



until a properly stained preparation is obtained. The complete 

 staining of connective tissues, in particular, requires this control 

 and adjustment to meet individual requirements. 



(c) The technique was developed in Dr. Lascano's laboratories 

 to overcome the problem of making satisfactory silver preparations 

 of hospital laboratory cirrhosis liver specimens already embedded 

 in paraffin wax. 



(d) The original paper should be consulted for more detailed 

 information and photomicrographs. 



Reference: Lascano, E. F. (i960), Stain Tech., 35, pp. 23-29. 



SILVER STAINING 



Enzymatic (pepsin or papain) removal of interfering 

 connective tissue elements prior to silver staining of 



nerves 



Solutions required: 



A. Pepsin powder, 1% in N/io hydrochloric acid 



(pHi-8-2-o) 



or 



B. Papain, 1% in veronal acetate buffer (pH 6 -0-6 '5) 



Technique: 



1. Incubate celloidin sections in solution A or B at 37° C. for 

 six to twelve hours. 



Note: Pieces of unembedded tissues, after washing in w^ater, 

 may also be treated as above, but a longer incubation time will 

 be necessary (from twelve to twenty-four hours). 



2. Wash the sections or pieces of tissue thoroughly with water, 

 then stain with silver nitrate as usual. 



3. Embed pieces of tissue in L.V.N, or celloidin before stain- 

 ing with silver nitrate. 



Results: 



Collagenous elements, which would otherwise mask the appear- 

 ance of nerves, are removed to permit a clearer and more accurate 

 identification of the nerves. 



°* 413 



