Saccharides (Carbohydrates) 267 



Alcohol or alcoholic mixtures are usually recommended as fixatives 

 for saccharides (exception: nucleic acids). Gomori (1952) writes that 

 theoretically, when glycogen is enclosed in a complex mixture of pro- 

 teins and lipids, it can be true that a good protein precipitant will coat 

 the glycogen with a protein membrane. This will be impenneable to 

 the large glycogen molecules and keep them m situ. He considers 

 Bouin's good but mercuric chloride is poor as a glycogen fixative. The 

 fixative should act and harden rapidly. Alcohol or acid fixatives form 

 glycogen in coarse droplets, while formalin-containing fixatives dis- 

 tribute the glycogen in fine granules. In some tissues (liver), unless the 

 tissue and fixative are chilled, enzymes can cause a loss of glycogen. 

 Although in most tissues glycogen is more stable, Gomori (1952) recom- 

 mends placing the tissue in fixative in the refrigerator. 



After proper fixation paraffin embedding is satisfactory, but after 

 deparaffinizing the moimted slides, rinse them in absolute ethyl alcohol 

 and protect the sections with a coat of 1% nitrocellulose to prevent 

 diffusion of the glycogen during staining. (Gomori, 1952) 



Glycogen Staining 



Best's Carmine 



fixation: avoid aqueous media (McManus and Mowry, 1958) 



absolute alcohol 9 parts. 



formalin 1 part. 



Start dehydration for embedding with 95% alcohol. 



MOUNTING slides: The author has preserved better localization of 

 glycogen by mounting paraffin sections with 95% alcohol in place of 

 water. As soon as sections are spread, drain off excess fluid and con- 

 tinue to dry. 



solutions: 



Best's carmine, stock solution: 



carmine, C.I. 75470 2.0 gm. 



potassium carbonate 1.0 gm. 



potassium chloride 5.0 gm. 



distilled water 60.0 ml. 



Boil gently: 5 minutes. Ciool. l-iker. Add: 



ammonium hydroxide 20. U ml. 



Lasts 3 months at 0-4 °C. 



