Topographic-quantitative Study of Bone Tissue Formation and Reconstruction 91 



(right) bones, namely humerus (H.), radius (R.), uhia (U.) and 3rd metacarpal bone 

 (3rd M.), are indicated on the x axis; recorded on the y axis are the means of the 

 values "/o NB/(PB + NB) of three consecutive cross sections of the mid-shaft taken 

 serially at 1 mm intervals. The numbers at the base of each couple of bars indicate 

 the mean percent reduction of the amount of osseous tissue (PB + NB) recorded in the 

 three mid-shaft cross sections of the inert bone compared to the contralateral mobile 

 bone taken as unity ( = 100). The maximum (Mx) and minimum (Mn) values of the 

 ratio between the relative amounts of labelled newly formed osseous tissue, recorded 

 for the left and right sides of the various pairs of bones studied, are reported for each 

 subject above the groups of bars. 



50- 



Mx r 



Mx 17 

 Mn 13 



3? c! 6^ 

 H. R. U. 

 After ZOd^QSj^ 



MRU. 

 After 5(7 days 



7 J 

 H. R. U. 

 After 180 days 



W ^-9 48 

 H. R U. 

 After 360 days 



Fig. 3 



It is concluded that: 



1. A remarkable loss of osseous tissue takes place in the cortex of inert and 

 denervated bones in comparison to the mobile homotypic bones. The degree of this 

 reduction varies in the shaft bones of each subject, and in each bone in subjects 

 sacrificed at different time intervals after operation. In general, the ulna undergoes 

 the greatest reduction. For equal periods of immobilisation, the degree of bone tissue 

 reduction is greater the younger the subject at the time of limb suspension and 



