Abstract
Methods have been described for the quantitative histochemical estimation of alkaline and acid phosphomonoesterase activities of sections of fresh frozen tissue. Both methods employ sodium β-glycerophosphate as substrate but are not limited to this particular substrate. The methods are essentially microbiochemical and permit the accurate estimation of enzyme activity in sections adjacent to those prepared for histological examination or for the histochemical localization of sites of activity by one of the conventional qualitative technics. The activities of these enzymes in sections of normal fasted rat liver 3-4 mm. in diameter and 20 microns thick are: 5.6 ± 0.7 mµg. phosphorus/µg. protein/30 minutes at pH 9.4 and 37°C. and 29.6 ± 4.6 mµg. phosphorus/µg. protein/30 minutes at pH 5.0 and 37°C.