A prosthesis wall for an artificial organ, e.g. an artificial arterial blood vessel, to be coated without gaps on one side with biologically active epithelial, e.g. endothelial cells is provided with a structure of open continuous micropores a few microns in size. The pore size is limited to between 0.1 and 3 microns, at least on the surface to be coated with cells with the thickness of the partitions between the pores being not more than 3 microns to permit a continuous layer of endothelial cells with prolonged and firm adhesion to the prosthesis to be subsequently formed.
