10 in fig1 designates overall a vascular implant 10 which has been produced by the process of the invention . a protein matrix 12 is deeply anchored in a structured material component 14 in the implant . the inner wall of the vascular implant 10 is formed by a protein membrane 16 which represents the boundary to the lumen 18 . the protein matrix 12 consists of protein fibres 20 with pores 22 . an adequate stability and suturability is conferred on the vascular implant 10 by the structured material component 14 , which is present like a framework in the protein matrix . the pores 22 , which extend in directed fashion , of the protein matrix 12 can be colonized uniformly with cells such as , for example , smooth muscle cells , and in vivo it is possible for cells to grow in from the surrounding tissue . on the other hand , the inner wall , or protein membrane 16 , of the vascular implant 10 can be colonized with endothelial cells because the protein membrane 16 provides a suitable surface for formation of an endothelial monolayer . it is noted at this point that the vascular implant 10 shown in fig1 represents only one exemplary embodiment . besides this , the invention can also be employed in other shapes and functions such as , for example , as patches for skin implants , as cylinder or rectangle for cartilage and bone implants or heart valves . it is possible by the process to produce implants with different layer thicknesses of the protein matrix . a particular temperature profile is applied in order to achieve a particular layer thickness of the protein matrix . in this connection , fig2 shows a diagram in which the dependence of the pore size taking account of the acetic acid concentration and the cooling rate is depicted . it is evident from the diagram that larger pores can be produced with a lower cooling rate ( see , for example , 0 . 5 k / min compared with 12 k / min ) and that , when the acetic acid concentration is simultaneously raised , the pore size was likewise larger than with a lower acetic acid concentration ( see , for example , at the cooling rate of 1 k / min : 1 . 5 % acetic acid : 85 μm pore size compared with 3 . 8 % acetic acid : about 110 μm pore size ). the use of the device is now shown by means of the example described below . a wide - mesh textured polyester net was knitted , cleaned and shrunk by known processes . the polyester net in collagen suspension was completely deaerated in a desiccator . a tubular collagen / collagen - elastin membrane with the desired internal diameter of the resulting vascular implant was produced from the collagen suspension or the collagen - elastin suspension by extrusion or by producing a flat collagen membrane and subsequent tube formation with collagen suture . this collagen / collagen - elastin membrane ( protein membrane ) was placed in the desired length on for example a metal tube ; the polyester net ( that is to say the structured material component ) was pushed over the protein membrane , and a second tubular shape was applied to the structured material component which , depending on design , can serve as cooling plate or for insulation . in a next step , a ( collagen / collagen - elastin ) suspension was introduced between protein membrane and structured material component . the arrangement was then cooled , i . e . the collagen / collagen - elastin suspension undergoes directed solidification — for example by a unilaterally controlled freezing step . for this purpose , the temperature of the metal tube , which now acts as cooling tube , is reduced at a constant cooling rate of , for example , 6 k / min . ethanol serves as cooling medium and is pumped continuously through the metal tube . after the freezing , the second shape is removed . the samples are stored at & lt ;− 45 ° c . for at least 12 hours and then freeze - dried . after a subsequent sterilization , the vascular prosthesis produced by the process of the invention and consisting of a collagen / collagen - elastin matrix , collagen / collagen - elastin membrane and a polyester reinforcement is ready for colonization by , for example , myofibroblasts , endothelial cells and smooth muscle cells in a cell reactor . as already mentioned , the implant is already liquid - impermeable , owing to the introduction of the protein membrane , when cells are applied . it was possible with the implant of the invention to reduce the colonization time until a cell monolayer formed to a maximum of four days .