Inorganic trimetaphosphatase as a histochemical marker for lysosomes in light and electron microscopy

A new cytochemical method is presented for the light and electron microscopic localization of lysosomes in mineralized and soft tissues. Inorganic trimetaphosphate is used as substrate in a lead chelate incubation medium at pH 3.9. Lysosomes in several tissues are strongly reactive, and reaction product is frequently present in Golgi saccules and GERL. The reaction can be differentiated from acid glycerophosphatase activity, is relatively insensitive to fixation and demineralization procedures, and the reaction is often complete after short incubation times.