A releasable connecting mechanism for a syringe, said mechanism including: a piston having a head portion with one or more radially projecting pins, said head portion being rotatable with said pins about an axis along said piston a plunger body having a recess formed within said body for receiving said head portion, said recess including one or more inwardly projecting flanges for guiding said pins to rotate said head portion relative to said body wherein, when said head portion is inserted into said recess, said flanges rotate said head portion to a locking position where said body resists disengagement from said piston, and when said head portion is further inserted into said recess, said head portion is released from said locking position and rotates to a release position allowing said piston to disengage from said body.
