456 



J. JOWSEY 





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B. 



Fig. 2. Microradiograph (A) and Ca^^ autoradiograph (B) of a cross 

 section through the mid-shaft of the femur of an adult rabbit with cortisone- 

 induced osteoporosis. The animal was killed \\ hours after Ca^^ injection, and 

 the isotope is heavily concentrated in areas of bone resorption. ( X 22. ) 



sorption, such as osteoporosis and renal failure, and also occasionallv 

 in normal bone (Fig. 3). Despite these indications that there may 

 be different rates of resorption in different areas, in the quantitative 

 measurements it has been supposed that an axerage \'alne is xalid. 



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Fig. 3. Microradiograph of a cross section through the mid-shaft of the 

 femur of a 15-year-old female with renal failure, showing the irregularity of 

 surface characteristic of rapid resorption at a, h, and c, and more normal 

 resorption at d and e. At g and / are two recently formed osteons with sclerotic 

 rings characteristic of cessation of new bone formation. (X 22.) 



