<正> The repairing capacities of bone matrix gelatin（BMG）

decalcified bonematrix（DBM）and deep frozen bone（DFB）were tested in experimental defects onskulls of rats.The healing of defects were judged by roentgenographic

histological and atomic absorption spectrophotometric methods.The healing ofdefects was most effective with BMG（P<0.01）

and DMB came next while thecapability of bone induction was very weak in DFB.In the BMG and DBMgroups

skull defects were completely healed in 12 weeks after the operation

but inthe DFB group healing was incomplete.The control group failed to healspontaneously.The results suggest that during the process of resorption of BMGand DBM

bone morphogenetic protein（BMP）was released by diffusion

whichinduced mesenchymal cells originating from the dura mater to differentiate intochondrocytes and osteobIasts

resulting in formation of new bone.The inducedosteogenesis is considered to be a complex process regulated not only by BMP butalso by various systemic and local growth factors.