A tissue prosthesis delivery device (10) includes an elongate, tubular introducer element (12), the element having a tissue piercing distal end (14) with an opening (16) arranged proximally of the distal end (14). A closure member (18) is associated with the introducer element (12) for opening and closing the opening (16) of the introducer element (12). An expansible prosthesis envelope (20) is received in a collapsed configuration within the tubular introducer element (12) to be deployed laterally of the introducer element (12) through the opening (16).
