THE STRUCTURE OF THE BONES 



21 



Zone of altered cartilage 



Vascular canals of the < 

 cartilage 



Endochondral centre of ossification 



Primitive cartilage 



FIG. 33. INTRACARTILAGINOUS OSSIFICATION OF A SHORT BONE. 

 A section of the cuboid bone of a new-born child. 



Eows of osteoblasts --- 



.. . ., Tissue of the primitive 



cranial membrane 

 'j'Z'.'t-' 



Osseous spicules 



FIG. 34. INTRAMEMBRANOUS OSSIFICATION OF THE BONES OF THE CRANIAL VAULT. 



Upper half of the parietal bone of a human fuetus in the eleventh week of intra-uterine life. 



Development of the Bones. 



