A syringe includes an elongate barrel having an open proximal end and a distal end that includes a fitting. It also has a plunger having a proximal end and a distal end, sized for slidable movement within the barrel thereby defining a chamber within the barrel. The plunger also has an elongate cavity therewithin that has a closed proximal end and an open distal end. The open end of the plunger is closed by a selectively releasable closure. The syringe has a hub that attaches to the barrel with a fitting conjugate to the fitting. The hub includes an elongate needle having a proximal end, a distal end and a fluid path therethrough. The needle is positioned in the passageway for slidable movement between a first position wherein the fluid path of the needle is in fluid communication with the chamber and a second position. The needle has a mount at its proximal end forming a seal with the chamber when the needle is in the first position. The syringe has a spring disposed about the mount biased to urge slidable movement of the needle from the first position. The syringe includes a latch disposed in the hub to engage the mount and retain the mount in the first position. The latch is releasable so that the spring urges the needle to move from the first into the second position within the cavity in the plunger, once the latch is released.
