The Origin of Bone Cells in Endochondral Ossification 35 



transplanted according to the usual technique. Autoradiographs of the fragments 

 before transplantation showed that the label was taken up by some cells of the zone 





\ . \^ 



% 



privcd of the pcriAoiulrium .iiul l.il.dlol with -iH-thymidi 



m 



I 



% 



i 



^ 



Mm. ^mL. 



Fig. 4. A Libelled transpl.int dcpmed nt perichondrium, observed two weeks attoi s;iitiin^ 1 he original trans- 

 plant was fully comparable with the situation given in Fig. 3. In the graft labelled osteoblasts and osteocytes 



can be seen 



of cell columns and most important no perichondrium appeared to have been left on 

 the fragments at all (Fig. 3). 



