tissues

Microscopic View of Spongy Tissues
trabeculae run in all directions endure stress and only a few cell layers thick
trabecular containirregularlyarrangedlamellae and osteocytesconnectedbycanalul
no osteons usesdiffusion




intra
membraneous

bonedevelopsfromfibrousCTmembraneswithmesenchymalcells

jjjime
beginsat 8weeks ofembryonicdevelopmentcranialbones and clavicle

endochondral
ofhyalinecartilage for all bonesbelow skull more complex
starts at 2nd month of development

2nd ossification
hyaline cartliedgeremainsonly onepiphyses
Mechanismsof Growth
longboneslengthen entirelythroughinterstitial
growth ofepiphysealplates
allbonesgr w in thicknessthroughappositional
growth
bonesstopgrowingin adolescenceearly adulthood except for somefacialbonesnosejaw
boneisdestroyed byosteoclastand laid down by
osteoblasts

epiphysealplateremainsthe same size throught
childhoodandgetsthinner in adulthood

appositionalgrowth
osteoblasts secretebonematrix atperiosteum
osteocytesdestroybonematrix atendo
steal