Diffusion of bone morphogenetic activity from the residue of collagenase digested bone matrix gelatin through interstitial fluid.

Bone morphogenetic activity is transmitted from the residue of a collagenase digest of bone matrix gelatin not only across cellulose acetate membranes but also through an interstitial fluid filled duplex diffusion chamber (a distance 300 + 2,000 mum). Collagenolysis enhances dissociation of the bone morphogenetic property of bone matrix and dissemination among mesenchymal cells proliferating in the host bed surrounding the diffusion chamber. The bone morphogenetic response is associated with secretion of interstitial fluid, enzymes, and fibrin as well as formation of new collagen fibrils beaded with coarse ruthenium red granules in the pores of the cellulose acetate membrane. Membranes with pore sizes too small to accommodate either new collagen fibrils or mesenchymal cell microvilli do not transmit the morphogenetic response.