A NEW ELECTRON MICROSCOPIC HISTO-CYTOCHEMICAL STAINING METHOD -DEMONSTRATION OF GLYCOGEN PARTICLES-

Abstract

For electron microscopic demonstration of glycogen particles in tissue sections, a new histochemical staining method is introduced as a substitute for stains such as periodic acid thiosemicarbazide silver proteinate. It is based on the fact that glycogen particles can be demonstrated with alkaline bismuth (A·Bi) solution alone and without periodic acid pretreatment.A. The staining mechanism involves a direct reaction where vic-glycol groups in glycogen compounds are oxidized into carboxyl groups and bismuth is reduced. The latter combines with the carboxyl groups to effect increased electron opacity of glycogen particles under electron microscopic observations.B. The glycogen particles can be observed even if periodic acid treatment is added on condition that the treatment be stopped within 10-15min. But glycogen particles disappear when the treatment lasts more than 30min. The treatment is not necessary even in theory because the A·Bi stainable vic-glycol groups are gradually decreased in proportion to the duration of the treatment.C. The technique is adapted to the observation under high magnification of the mode of α-D-glucopyranose arrangement in glycogen compounds because the bismuth deposit has a high electron opacity due to the high atomic number of bismuth and is positioned only in the vic-glycol group of the glycogen compound.D. The staining technique is remarkably simple as staining needs to be carried out only once, in contrast with previous methods.This A·Bi staining technique permits excellent high contrast observation of glycogen particles in the cytoplasm of liver cells and myocardial muscle cells which could be seen to consist of fine granular substructures.