silk materials described herein referring to fig6 and 7 a polymeric sheath can serve as a sheath 14 a that is provided on a mandrel 22 and has stent 12 affixed thereover the mandrel and stent can then be placed into an oven for a time sufficient for sheath 14 a to be inextricably melted within the open spaces of stent 12 upon removal of the stent and sheath combination a silk sheath 14 is placed thereover a cross section of this assembly is provided in fig8 it is evident that a polymeric sheath can easily be provided on an exterior surface of stent 12 as well with a silk sheath on a luminal surface of the stent either or both of the luminal and exterior surface sheaths 14 and 14 a may be provided with an adhesive thereon which permits adherence of the tubular structures to one another through the stent openings and simultaneously allows adherence of stent 12 to either or both of the structures the adhesive may be a thermoplastic adhesive and more preferably a thermoplastic fluoropolymer adhesive such as fep a suitable adhesive provides a substantially sealed tube without significantly reducing longitudinal and axial compliance the present prosthetic materials can also be implemented in an implantable vascular prosthesis or graft u201c vascular graft u201d can mean conventional and novel artificial grafts made of this material constructed in any shape including straight tapered or bifurcated and which may or may not be reinforced with rings spirals or other reinforcements and which may or.