A device for the preparation of a graft in which a flexible tubular porous base member is suspended within a tubular enclosure with means for sealing the enclosure and for the introduction of blood while removing air from the enclosure co-incident with the introduction of blood and in which the porous tubular base member onto which the blood is clotted in forming the graft embodies axially spaced corrugations to permit stretchability for working the graft to enhance permeation of the blood and to permit easy bending without collapse.
