RESORPTION WITHOUT OSTEOCLASTS (OSTEOLYSIS) 541 



sections, the lamellar arrangement of the bone was made apparent 

 by the presence of alternating bands of more and less stained matrix 

 (Fig. 14). 



Rats which were 10 to 12 days pregnant revealed a similar picture 

 but with great variations from one animal to another. 



Pregnant rats injected with Para-Thor-Mone (Fig. 15) revealed an 

 exaggeration of the above-described phenomenon, i.e. a greater 

 proportion of hypertrophic osteocytes, surrounded by strongly baso- 

 philic matrix. 



Alpharadiography. Islands of low density were observed mid- 

 way between the periosteal and marrow borders of the diaphysis or 

 closer to the marrow border. 



It was evident that the areas of low density in the alpharadio- 

 graphs matched the basophilic matrix and concentrations of hyper- 

 trophic osteocytes in the stained sections (Figs. 14 and 15). 



Dogs 



Para-Thor-Mone. X-ray microradiography . The trabecular bone 

 of normal dogs revealed the presence of a denser white band in the 

 near center (Fig. 17). Some lacunae in this area appeared wider 

 than at the periphery. Some of these were also closer to one an- 

 other; some were even confluent ( Fig. 17 ) . In compact bone, larger 

 lacunae were observed in the interstitial lamellae and also at the 

 periphery of some of the bigger osteons. 



In the dog which received 100 units of Para-Thor-Mone, it was not 

 possible to detect any significant change in the microradiographic 

 pattern. 



In those which received 600 units over 3 days, there was no im- 

 portant modification of the image in sections of the tibia. However, 



Figs. 5 to 8. Alpharadiographs from sections as above. ( X 144.) 



Fig. 5. Rickets. 



Fig. 6. Rickets plus Para-Thor-Mone. 



Fig. 7. Rickets plus vitamin D. 



Fig. 8. Rickets plus vitamin D-Para-Thor-Mone. 



The periosteum is in the lower part of the pictures. 



