480 CHARLES R. STOCKARD AND E. M. VICARI 



onstrated that the disease was duo to overfunction of the 

 parathyroids, since beneficial results followed the extirpation 

 of parathyroid tumors. The pathogenetic connection between 



the disease and the overproduction of the parathyroid hor- 

 mone was clearly demonstrated by the researches of Jane, 

 Bodansky and Blair ('30) who showed that hone destruction 

 similar to osteitis fibrosa in man could be induced in guinea 

 pigs and dogs by excessive dosing with the Collip hormone. 



A fact of particular interest in connection with osteitis 

 fibrosa is that it occurs not only as a generalized disease but 

 may also be quite sharply localized. The histologic structure 

 of the diseased bone in both generalized and localized osteitis 

 fibrosa is exactly the same. It has been suggested that 

 trauma and mechanical effects of function in certain parts 

 of the skeleton may cause these places to be more sensitive 

 in their response to the parathyroid hormone, yet no direct 

 evidence for such an explanation is available. It is significant 

 that tumors of the parathyroids have not been found in 

 localized osteitis fibrosa and that the blood calcium level is 

 always normal. We thus have in the generalized state of this 

 disease a reaction which may be definitely brought about by 

 hormone overstimulation, while the same disease may ap- 

 pear in a localized region although no disturbance in hormone 

 balance has occurred. There may be a genetic basis for the 

 localized osteitis fibrosa reaction just as we have shown for 

 the achondroplasic screw-tail in an animal with no further 

 symptoms of chondrodystrophy. It is further suggested that 

 generalized osteitis fibrosa resulting from disturbed calcium 

 metabolism associated with parathyroid tumors and hyper- 

 trophy might be a definite genetic disease appearing during 

 certain life periods only in those individuals carrying the 

 mutation for parathyroid tumor and the associated disturb- 

 ances. 



The foregoing digression from our immediate subject is 

 intended to emphasize the fact that the parathyroid glands 

 are organs of importance in all considerations of growth and 



