the wall of a prosthesis has a region which modulates communication through the porosity of the wall . the prosthesis is unitary , but may be assembled in successive bodies which are coalesced , so that the porous microstructure changes distinctly at stages through the thickness dimension of the wall . one embodiment is formed entirely of fluoropolymer , and has at least one surface adapted to support tissue regeneration and ingrowth . the modulation region is a stratum of high water entry pressure that reduces pulsatile hydraulic pressure transmission , or locally alters fluid - born - distribution of biological material through the wall and allows more natural gradients for tissue regeneration and growth in the outer region of the wall .