TISSUES. 



system. Cells with lamellae are added centripetally 

 to this outer row and thus ultimately complete the 

 Haversian system, leaving a 

 small central canal contain- 

 ing vessels and a nerve. 



Ossification begins in the 

 center of the cartilage shaft 

 and proceeds gradually 

 toward each end, so that all 

 the above changes occur at 

 one and the same time. 

 After birth these changes go 

 on at the ends of the bone, 

 so long as it keeps growing. 

 During this period the bone 

 is made thicker by deposits 

 from the periosteum forming 

 the circumferential lamellae of 

 bony shafts. These lamellae 

 are added without the inter- 

 vention of a cartilage stage 

 and therefore represent intra- 

 membranous development. 



Regeneration of Bone. 

 The embryonic process of 

 developing bone is repeated 

 every time a broken bone 

 heals. As a rule the carti- 

 lage stage does not intervene. 



. c .-, i .. Fig. 51. Longitudinal 



A synopsis of the healing 5cc ^ n trough area of 

 process of a simple fracture ossification from long 



bone of human embryo 

 IS as follows: (Huber). 



