DIFFERENTIAL OSTEOCLAST ACTIVATION IN ENDOCHONDRAL AND INTRAMEMBRANOUS BONE

Osteoclast activation within the temporal bone leads to hearing loss i n a variety of Pathologic conditions, including otosclerosis, osteogen esis imperfecta, Paget's disease of bone and chronic otitis media. Alt hough endochondral (EC) bone is remodeled in these disease, it is rela tively more resistant to remodeling when compared to intramembranous ( IM) bone. In this study, localized bone resorption and remodeling were induced on the inner surface of the middle ear by pressurization with air to 10 mm Hg above atmospheric. Osteoclast surface increased in IM bone, but not in EC bone. This study supports the concept that there may be fundamental differences between EC and IM bone and that EC is m ore resistant to pressure-induced localized resorption than IM bone.