The syringe manufacturers is characterized by an elongated barrel which is closed
on one end and a hollow plunger assembly which comprises the needle housing and houses the needle extension and retraction apparatus. The closed end of the barrel comprises a generally convex inner surface to facilitate expulsion of undesirable gases as is standard practice when preparing contents of a syringe manufacturers immediately prior to use. In a preferred embodiment, the closed end also comprises a closable and sealable access port through which the barrel may be prefilled.