HISTOCHEMICAL EVIDENCE OF PROTEOLYSIS IN BONE: THE INFLUENCE OF PARATHORMONE

Proteolytic activity has been revealed at the level of the large osteocytes of young chick and rat bone by digestion of gelatin in a photographic emulsion substrate. The reaction was enhanced by pretreatment of the animals with parathyroid extract. The reaction was inhibited by addition to the incubating medium of sodium fluoride or potassium ferrocyanide. It was also inhibited by fixation in ethanol-formaldehyde acetic acid. The present results seem to confirm and explain further the resorptive potential of the mature osteocytes.