The in vivo synthesis of connective tissue by fibroblast or fibroblast precursor cells ensconced within a biocompatible scaffold is disclosed. The cells are preferably present in a biocompatible scaffold such as gelatin and placed between two other biocompatible scaffolds such as collagen sponges soaked with a collagenic amount of a member of the TGF-.beta. family of proteins. This composition is then implanted in a host to produce cranial sutures, periodontal ligament or other fibrous tissue structures in vivo.