Optimization of PAS reaction and similar Schiff`s based methods for glycogen demonstration in liver tissue. 

Purpose: Demonstration of glycogen in tissue has valuable diagnostic significance in several lesions, including certain tumors. Histochemical staining of glycogen with Schiff's dependent methods is affected by the type of fixative, the temperature of fixation, and oxidizing agents. This study aimed to evaluate different fixatives, temperatures of fixation, and oxidizing agents with variable durations of treatment to be used with Schiff's reagent for glycogen demonstration. Methods Archived paraffin blocks prepared from one rabbit's liver were used and 340 paraffin sections were stained with different oxidizers-Schiff methods. Results For tissues fixed at 4°C: 10% NBF, 80% alcohol, and Bouins's solution provided good staining results with PAS reaction. For tissues fixed at RT: both 10% NBF and 80% alcohol provided good staining results with PAS reaction. The other oxidizing agents provided poor results with all fixatives and temperature of fixation, with two exceptions of satisfactory staining results for 5% chromic acid for 10 minutes at both room temperature (RT) and 60°C. Conclusion Both 10% NBF and 80% alcohol seem to be the fixatives of choice for glycogen when the PAS reaction is used. However, Bouin's solution could provide good results at 4° C.