I had an opportunity to visit U.S. Naval Tissue Bank and observed tissue procurement and preservation by freeze-drying method and its clinical application while I stayed in the Naval Hospital, Bethesda in 1954. The freeze-dried tissues, especially bone graft, has shown excellent bone repair experimentally and clinically. Recently the mechanisms of osteoinduction have observed by many researchers and isolated the substance, bone morphogenetic protein, and clarified the interaction between BMP and the determined or inducible osteoprogenitor cells.