246 



VITAMIN D GROUP 



of the operation of mechanical forces on the newly and poorly formed 

 bone. Groups of cells may be compressed, a trabeculum may be bent 

 or doubled up on itself, the cartilage column at the periphery may fan 

 out to extreme angles, and there may even be a displacement of the up- 

 per metaphysis against the bone shaft so that the long axis of both 

 structures form an angle (Fig. 23). Moreover, since the human being seldom 

 suffers from complete absence of vitamin D, one finds evidence of transient 

 periods of healing, followed by recurrence of the ricketic process. To add 



Fig. 22. Metaphyseal area. Irregular masses of cartilage cells, some swollen, some 

 compressed; compressed trabeculae of uncalcified osteoid tissue; irregular invasion 

 of cartilage by blood vascular marrow which shows early fibrous changes; some 

 degenerated cartilage and ghost cells; osteoid surrounding the invading marrow. 



to the complexity of the picture, one may find evidence also of other vita- 

 min deficiency such as deficiency of vitamin C, or, less often, deficiency of 

 vitamin A and vitamins of the B complex. Deficiency of vitamin C may 

 lead to hemorrhage, osteoblastic degeneration, and fractures of newly calci- 

 fied trabeculae. 



This variable and unpredictable histologic appearance is reflected in the 

 roentgenographs of the bones. Cupping and enlargement of the space be- 

 tween the epiphysis and the end of the shaft due to the transparency and 

 swelling of the metaphysis is most obvious. Cortical spurs or linear exten- 

 sions of the cortex w^hich hug the proliferative cartilage may be an early 

 sign. Frayings, consisting of thread-like shadows extending from the end 



