Comparison of Methods for Demonstrating Glycogen Microscopically

Abstract

3 methods for the microscopic demonstration of glycogen are compared: namely, Best''s carmine, the I method, and Bauer''s modification of the Feulgen technic. The lability of glycogen necessitates immediate fixation, small pieces of tissue, and agitation of the fixative. The fixative recommended consists of 9 parts by vol. of absolute ethyl alc. to one part of 40% formaldehyde neutralized with MgCO3; the alc. in this formula may be saturated with picric acid if desired. After fixing, the tissue should be washed in absolute alc. and embedded in paraffin or celloidin, taking care to avoid overheating of blocks or sections. A sharp knife should be used in sectioning. The Best''s carmine technic is employed by staining first with hematoxylin, then for 20 min. in: Best''s stock soln. (prepd. by the usual formula, using Grubler''s carminum rubrum optimum), 10 cc; conc. ammonia, 15 cc; methyl alcohol, 30 cc; used fresh after agitating and without filtering. The I method calls for Lugol''s aq. I. The Bauer-Feulgen method calls for sections mordanted 1 hr. in 4% aq. CrO3 and washed in water 5 min., followed by 10-15 min. in: a suitable basic fuchsin (e.g., Griibler), 1 g.; warm dist. water, 100 cc, with filtration of soln. while still warm; normal HCl, 20 cc., added after cooling; NaHSO3, 1 g.; ripened to a straw or amber color for 24 hrs. in the dark. After this bath the sections are rinsed 1