PROTOTYPE I: DISPOSABLE SYRINGE WITH DECREASED PLUNGER ROD DIAMETER. The risk of sterile compartment contamination via plunger rod is excluded because narrowed plunger rod has no contact possibility with internal surface of syringe barrel. Narrowed plunger rod axial movement is constrained through axial moving of piston of special construction. 

PROTOTYPE II: DISPOSABLE SYRINGE WITH PLASTIC COVER OF PLUNGER ROD. The risk of sterile compartment contamination is excluded through use of foil cover, which protects plunger rod against external environment. Elastic cover is attached to the end of plunger rod and open end of syringe barrel. This cover surrounds hermetically the (pushed out and in) plunger rod.