A non-reusable retractable safety syringe is provided which has a hollow plunger and a seal member carried thereon. The provision of the plunger and the seal relative to the barrel permits the plunger, with sufficient strength, to carry applied pressure through the device during injection of a medicinal or other fluid into a patient, and yet permit the seal disposed at one end of the plunger to have maximum sealing integrity between the plunger and a cylindrical barrel disposed around the exterior of the plunger, to abate leakage of the liquid in a chamber within the barrel, as the plunger is manipulated from an expanded position to an expended position and thereafter to a third, or collapsed position. Designs for securing the seal relative to the plunger are disclosed. The syringe may be used to insert and/or withdraw fluid relative to the patient.
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