RAREFYING DISEASE OF THE SKELETON 



401 



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FlG. 5G. Microradiograph of the endosteal surface of the cortex showing 

 old bone in a low-density osteon with a sclerotic inner wall and calcified 

 osteocytes (arrow on the right). The arrow near the center indicates an en- 

 larged lacuna with a rarefied zone of matrix around it. The arrow on the 

 left points to hypermineralized interstitial bone in which many of the lacunae 

 are filled with calcium salts. The osteon with the large vascular channel in the 

 lower right corner of the picture has a sclerotic inner ring; this occurs when 

 bone formation ceases before the system is half closed; quantitatively, this 

 appears more frequently in osteoporotics than in nonosteoporotics and causes 

 increased porosity of the cortex. (X approx. 400.) 



National Institutes of Health, United States Public Health Service, 

 1962 ) was administered by intramuscular injection of 2 mg per day 

 from the 50th to the 65th day; this produced 2.0 gm of positive 

 nitrogen balance but little or no improvement in the negative cal- 

 cium and phosphorus balance; the urinary calcium excretion, nor- 

 mally onlv 50 to 100 mg per dav in aged osteoporotics, increased 

 from 100 to 200 mg per day. These effects of growth hormone were 

 associated with further decline in weight, and probably did not 



