A syringe for a fluid comprises a cylinder, a piston portion arranged in the cylinder and slidable on its inside, and an operating means connected to the piston portion for sliding thereof. The operating means projects from a first end of the cylinder and the cylinder has at a second end an inlet and outlet part for said fluid. Moreover a sealing means is connected in a contamination-free manner to the cylinder in the area of the first end thereof and extends into the cylinder to isolate, sealed against contamination, the inside of the cylinder from the environment.