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