STAINING, PRACTICAL AND THEORETICAL 



Technique: 



1. Unstained, control sections of material which have already 

 been demonstrated as PAS-positive are taken though alcohols to 

 distilled water. 



2. Immerse in the above reagent for fifteen to thirty minutes 

 ati5°to37°C. 



3. Rinse in distilled water. 



4. Treat exactly as the original sections, which were found to be 

 PAS-positive. 



Results: 



If the substance which was PAS-positive in the original sections 

 is not stained after the digestion test, it is either glycogen or 

 starch. 



Notes: 



{a) Instead of the diastase solution, saliva may be used. 



{b) Sections used in the digestion test should, for preference, 

 not be more than lOjU, thick, and they should not be coated with 

 celloidin as this will prevent the penetration of diastase. If celloidin 

 embedded material is used, the celloidin should be removed from 

 the sections before the diastase test is applied. 



References : 



Gomori, G. (1952). 



Lillie, R. D. & Greco, J. (1947). 



Iodine test 



For differentiating between glycogen and starch 



Solutions required: 



A. Lugol's iodine 



B. Iodine crystals . . . . . . 2-5 gm. 



Absolute alcohol . . . . 100 ml. 



C. Origanum oil 



Technique : 



1 . Carry sections down to 70% alcohol in the usual way. 



2. Stain in Lugol's iodine solution for ten minutes. 



354 



