How Bone is Formed in Humans - Douglas' Questions

[atrec]

I am a colege student, we are going to have a test after holidays, i am worried because I still don't know a lot of things. Could you tell me how bone is created in human ?
I know there are tow stages bone is formed: membrane, and endochondrea.
I am still stuck at how to say these two stages in a more particualar way. I haven't found any source s so far on teh internet.
Thank you.

-Douglas

 

[kalladin]

bone formation

A quick search on Google for "bone formation" would have given you most of what you are looking for. The gist of it is that bone formation (or osteogenesis) occurs in two main processes:

Intramembranous Ossification involves the transformation of mesenchymal connective tissue into bone; no cartilage model is required. This process occurs in the development of flat bones and other irregular bones. Basically, osteoblasts migrate to the connective tissue and surround themselves with bone matrix that they secrete.

Endochondral Ossification which is the main process of bone formation, involves the sequential replacement of hyaline cartilage with bony tissue. Most people refer the hyaline cartilage in this process as a "cartilage model" for bone formation. The perichondrium of the hyaline cartilage becomes infiltrated with blood vessels and osteoblasts which transform the perichondrium into a periosteum. A compact bone collar is formed by osteoblasts surrounding the cartilage, and the cartilage in the center also becomes transformed into spongy bone, where the cells die and the extracellular matrix becomes calcified. There are a few zones that are created when the cartilage becomes spongy bone: zone of reserve cartilage, zone of proliferation (where the chondrocytes undergo rapid cell division), zone of hypertrophy (where the cells swell up), zone of cell death, and the zone of provisional calcification (where the matrix becomes calcified).

 

[atrec]

Thanks Kalladin a lot for your reply..