RAREFYING DISEASE OF THE SKELETON 305 



(in autopsy subjects), there were patches of basophihc metachro- 

 matic, acellular necrotic bone that predisposed the patient to a 

 spontaneous fracture. 



The aboxe clianges also ojcurred in nonosteoporotic bcue from 

 both men and women of comparable age, but quantitatively the 

 degree was significantly less than in osteoporotic subjects (Table 

 VI). The osteoc\'tes in inner lamellae around blood vessels averaged 

 6.5 cells per high-power field in nonosteoporotics and 2.7 in osteo- 

 porotics. In the outer lamellae, the outstanding difi^erence was in 

 the number of retracting osteoc\tes, 6.0 and 3.7, and calcified osteo- 

 cytes, 3.0 and 1.5, in osteoporotics and nonosteoporotics respectively. 

 In the interstitial lamellae, the average number of enlarged empty 

 lacunae was 28.2, compared with 22.0. To judge from the appearance 

 of increasing amounts of bone with emptv lacunae with incieasing 

 age and with chronic peripheral vascular disease, it was assumed 

 that this condition represents devitalized bone from prolonged cir- 

 culatory insufficienc)' (Sherman and Selako\itch, 1957). We have 

 reviewed the biopsy sections of our previously reported cases ( Urist 

 et ah, 1962) and observed that osteocytes move to one side and 

 then enlarge the lacuna bv absorption of matrix between the canalic- 

 uli, possibly through the action of a proteolvtic enzvme. Later, the 

 cell undergoes autolysis, and an emptv enlarged spherical (rather 

 than stellate and ovoid) lacuna remains. These morphologic changes 

 were unspecific l^ut approximately 30 per cent more extreme during 

 middle-aged life in patients with severe osteoporosis (Figs. 5B to 

 51). 



Quantitative analyses of oxytetracycline in the biopsy sample by 

 the method of Ibsen et al. ( 1963) revealed 4 y per gm of bone. This 

 represented the amount deposited in the skeleton in Case No. 7 

 after infusion of 3.0 gm in a period of 45 days. This was 3.2 y less 

 than the amount to be expected, inasmuch as the average nonosteo- 

 porotic deposited 2.4 y after one infusion of 1.0 gm. Fluorescent 

 microscopy demonstrated that very few osteons, approximately 5 

 per cent of the total number in the section, were growing and re- 

 moving oxytetracychne from the extracellular fluid; in control sub- 

 jects of comparable age, approximatelv 10 per cent were reactive. 

 Examination of the active osteons by white light microscopy re- 



