Fragments of the parietal bone and tibia of fourteen young dogs were studied by x-ray microradiography of undemineralized sections, alpharadiography, and acid mucopolysaccharide staining of demineralized sections. Eight of these dogs received parathormone in different doses and were killed after intervals ranging from three hours to four days.
In the parathormone-treated animals, sites of resorption (osteolysis) were recognized in the middle of the trabeculae of cancellous bone and in the interstitial lamellae of compact bone.
These sites were characterized by more numerous enlarged and confluent lacunae inhabited by hypertrophic osteocytes containing metachromatic material and surrounded by basophilic or metachromatic matrix of lower density.
A dose of 300 units of parathyroid extract and a dose of 1000 units over three hours did not produce osteolysis.
A dose of 600 units over three days and to a greater extent a dose of 1000 units over twenty-four hours produced the effects described.
Osteocyte hypertrophy and hyperactivity caused by parathormone were often followed by degeneration and death of the cells.