MICRORADIOGRAPHY OF BONE RESORPTION 



465 



Fig. 9. Microradiograph of a cross section through the femur shaft of a 

 12-year-oId male with osteogenesis imperfecta. The cortex is thin and there 

 is a high proportion of unremodeled primary bone. Compare with 15-year-old 

 male in Fig. 5. (Formation 9.0 per cent, resorption 54 per cent.) ( X 6.) 



leaching out of mineral is unsure. The surfaces of most osteons are 

 lined with uncalcified osteoid tissue of great thickness. The presence 

 of osteoid tissue does not always indicate bone formation; in rickets 

 and hypoparathyroidism the low blood calcium levels may cause 

 failure of mineralization of osteoid tissue that has been laid down 

 some time ago, and this may be true in other abnormalities or even 

 in normal bone. It is worth while to point out the differences be- 

 tween the appearance of the osteocyte lacunae in rickets and that of 

 the somewhat irregular and enlarged lacunae of the osteocytes in 

 rapidly growing or woven bone (Fig. 1), where the walls of the 

 lacunae are smooth and sharply defined and the canaliculi normal 

 in diameter in contrast to tlie fuzzy appearance of the osteocyte 

 lacunae and involvement of the canaliculi seen in rickets. This ap- 

 pearance is also seen in osteomalacias and in the early development 

 of Paget's disease. 



