RESORPTION WITHOUT OSTEOCLASTS (OSTEOLYSIS) 551 



its salt content as estimated by x-rav microradiograpln' is not nni- 

 form (Fig. 21). 



The large osteocytcs (Figs. 11 to 13), more centrally located and 

 older, show a hvpertrophy which is mostly cytoplasmic. These cells 

 contain material which induces the phenomenon of metachromasia 

 with toluidine blue. The capsule which surrounds their lacuna con- 

 tains similar material which can be stained by azur, Alcian blue, and 

 neutral red. The adjacent organic matrix contains little or no meta- 

 chromatic material under normal conditions. 



X-ray microradiographs have revealed that there is generally a 

 low concentration of bone salt around the hypertrophic osteocytes. 

 Engfeldt and Zetterstrom (1954) and Engfeldt et al. (1956) inter- 

 preted this phenomenon as "newly formed areas associated with 

 resorption cavities, in which the osteocytes are often surrounded by 

 a large irregular zone containing small amounts of mineral salt or 

 none at all." 



Heller-Steinberg ( 1951), Rutishauser and Majno (1951), and also 

 Lipp (1954) have recognized changes in the mucopolysaccharide 

 content of the lacunae and their border which they have considered 

 to be associated with resorption. 



Alpharadiography of demineralized bone sections has revealed the 

 surprising fact that the youngest part of the trabeculae or of the 

 osteons (Figs. 8, 20, 22, and 24) is the densest organic part. It has 

 also shown that in the more mature fraction, islands of low density 

 containing large lacunae correspond to the areas of low mineral con- 

 tent which appeared in the x-ray records. 



Fig. 25. Lacunar resorption in trabecular bone (skull). The enlarged 

 lacunae are surrounded by occasionally confluent areas of low density. X-ray 

 microradiograph. (X 180.) 



Fig. 26. Alpharadiograph of a demineralized section of a portion of cranium 

 from a dog subjected to EDTA venoclysis. Notice dense border of osteonic 

 canal; lower density and fibrillar appearance of interstitial area underneath; 

 enlarged lacunae and distended canaliculi, upper right. (X 110.) 



Fig. 27. A portion of human diaph\seal humerus from a patient with para- 

 thyroid adenoma. Notice enlarged lacunae and adjacent low-density matrix. 

 Alpharadiograph of demineralized section. ( X 110.) 



Fig. 28. A portion of diaphyseal bone from a child suffering from osteo- 

 genesis imperfecta. Notice numerous enlarged and confluent lacunae and low 

 bone density. X-ray microradiograph of mineralized section. (X 110.) 



