The morphological alteration of particulate glycogen by en bloc staining with uranyl acetate

En bloc staining with unbuffered solutions of aqueous uranyl acetate prior to dehydration greatly altered the appearance of particulate glycogen in human skeletal muscle from cases of McArdle's disease, embryonic mouse myocardium, and chick glycogen body. Some of the effects, in particular the extraction of glycogen particles, could be duplicated by a sodium acetate-acetic acid buffer (pH 4.6). However, partial aggregation of carbohydrate material was produced only by solutions of uranyl acetate, suggesting that the heavy metal exerted effects which were independent of pH. The pattern and degree of glycogen alteration by uranyl acetate differed somewhat between the glycogen body and both skeletal and cardiac muscle. Though these differences are unexplained, the detrimental effects on the morphology of glycogen in all tissues studied indicate that en bloc staining with unbuffered aqueous uranyl acetate should not be considered an innocuous procedure. Examples are presented to indicate that acid extraction of glycogen may be a useful procedure for the differentiation of ribosomes from glycogen within muscle tissues.