Abstract
Aminopeptidase activity contained in healing fractures was studied histochemically in fibrous, caritlaginous and osseous callus from rat long bones. The substrates used consisted of amino acid β-naphthylamine compounds, i.e., L-alanine, L-leucine, L-arginine, DL-methionine, L-proline and L-alanine-4-methoxy compounds. The aminopeptidase was intensely confined to fibrous and cartilaginous callus cells and was less reactive in ossous callus. Osteoclasts and chondroclasts were devoid of the enzymatic activity irrespective of high amounts of acid phosphatase and succinate dehydrogenase. No significant differences for the aminopeptidase activity were observed in callous tissue when several amino acids compounds were used as substrate.
