A NEW TECHNIQUE FOR AFFIXING FRESH FROZEN SECTIONS TO COLD, UNTREATED GLASS SLIDES AND ITS APPLICATION TO HISTOCHEMICAL LOCALIZATION OF LOW-Km ALDEHYDE DEHYDROGENASE ACTIVITY, INHIBITED BY CYANAMIDE, IN MOUSE LIVER

A simple procedure, called the “cold acetone (-70°C) -dropping affixation technique”, for affixing fresh, frozen sections to cold, clean, untreated glass slides is described. A few drops of absolute acetone (-70°C) were dropped with a precooled pipet to the sections placed on the slides, and the acetone on the slides was absorbed immediately with a cold filter paper. The slides with the sections were left in a cryostat for approximately 30 min, so that the sections were affixed firmly to the slides. By this method we could prevent the diffusion of low-Km aldehyde dehydrogenase (ALDH) from the sections. The localization of low-Km ALDH activity in the hepatic lobule of normal mice was studied histochemically with the nitroblue tetrazolium (NBT) method. Reaction products, purplish-blue formazan showing the enzymatic activity, were found mainly in the centrilobular zone. Cyanamide (5 mM) inhibited the low-Km ALDH activity, whereas the high-Km ALDH activity was unaffected even by 10 mM cyanamide.