Changes

***Fine collagen fibres in concentric or parallel laminae

***Fine collagen fibres in concentric or parallel laminae

***Two main types:

***Two main types:

****'''Compact bone''' (cortical)

****'''Compact bone (cortical)'''  

*****Forms 80% of total bone mass

*****Forms 80% of total bone mass

*****Consists of cells and interstitial substance - 30% ossein (type of collagen) and 70% minerals, especially calcium phosphate

*****Consists of cells and interstitial substance - 30% ossein (type of collagen) and 70% minerals, especially calcium phosphate

*****Forms the shell of long bone shafts - contain [[Haversian systems]]

*****Forms the shell of long bone shafts - contain [[Haversian systems]]

****'''Cancellous bone''' (spongy or trabecular)  

****'''Cancellous bone (spongy or trabecular)'''

*****Made up of plates, tubes or bars arranged in lines of stress

*****Made up of plates, tubes or bars arranged in lines of stress

*****In vertebrae, flat bones and epiphyses of long bones

*****In vertebrae, flat bones and epiphyses of long bones