Osteoclast changes induced by lead poisoning (saturnism).

This paper reports the results of histological, histochemical and electron microscopic investigations, and of electron probe analysis, carried out on bone cells of tibiae and femurs of lead-poisoned collie puppies. The most important changes were found in osteoclasts. They were increased in number, showed intranuclear and intracytoplasmic inclusion bodies, and frequently had shrunk, pyknotic nuclei and were detached from bone matrix. Organic components were histochemically demonstrable in the inclusion bodies, which consisted of a central core, peripheral filaments and intrinsically electron-dense granules. Lead was detected in the inclusion bodies by electron probe elemental analysis: Pb-L alpha pulses in the regions with inclusions are four times higher than those in the cytoplasm. Osteoblasts and osteocytes did not contain inclusion bodies, probably because in them lead does not reach a concentration sufficiently high to induce inclusion formation. On the contrary, this concentration can be reached in the osteoclasts when, during bone resorption, they accumulate the lead salts previously incorporated in the bone matrix.