An apparatus is disclosed for the reception of a surgical instrument inserted through a cannula assembly. An orifice in a seal member defines a central longitudinal axis in general alignment with the cannula assembly. The seal member includes an elastic member for engaging the surgical object about the orifice and forming a fluid-tight interface. A fiber loop is at least partially embedded in the elastic member and serves to compress central portions of the elastic member around the instrument. The fiber loop may form a loop around the orifice and may cooperate with other fiber loops similarly embedded in the seal.