Endochondral ossification

Endochondral ossification

    - means replacement of cartilage by bone material which happens in 5 steps:

a. development of the hyaline cartilage model of the later bone
                by mesenchymal cells; differentiate into chondroblasts which
                secrete cartilage matrix, mostly in form of collagen fibers
           

b. chondroblasts differentiate into chondrocytes; a pH change in the
                cartilage matrix due to bursting chondrocytes triggers a process
                called bone calcification
           

c. primary ossification centers occur which proceed inwards; the
                periosteum forms plus growth of periosteal capillaries occurs
                → bone tissue replaces most of the cartilage matrix 
                → ossification is a biomineralization process
           

d. entering of epiphyseal arteries into the epiphyses trigger the
                 formation of secondary ossification centers outwards
           

e. the hyaline cartilage that covers the epiphyses forms the articular
                cartilage and the epiphyseal plate; remaining hyaline cartilage forms
                the epiphyseal plate
        - most bones of the skeletal system are formed this way
        - know the formation of articular cartilage and the epiphyseal plate of a typical bone

"Ossification begins during the 6th and 7th week of embryonic life and continues throughout adulthood.."