Abstract: The present invention relates to an apparatus and a method for sealing a puncture in a tubular tissue structure or the wall of a body cavity. More specifically, the present invention is directed to an apparatus and method for sealing a puncture site in the wall of a tubular tissue structure, or in the wall of a body cavity with submucosal tissue or another extracellular or matrix-derived tissue capable of remodeling endogenous connective tissue in vivo. The submucosal tissue or another extracellular matrix-derived tissue is inserted into the puncture site as a sheet on an introducer element such as a needle, a cannula, a guide wire, an introducer element adapted for dialysis, an introducer element adapted for catheterization, a trocar, or any other introducer element used to access the lumen of a tubular tissue structure or used to access a body cavity.