A syringe comprising: a) a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end; b) a stopper configured to be received within the open end of the syringe barrel, the stopper comprising: i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof, wherein the flexible roof is flat or the closed front end of the main body portion includes a first angled portion and a second angled portion forming a single conical surface that extends toward a tip providing the closed front end; and ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and c) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end having a radially extending member configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end, wherein, when fluid pressure is increased inside the syringe barrel during an injection, the flexible roof expands in a radial direction toward an inner wall of the syringe barrel, the first perimetrical skirt is forced against the inner wall of the syringe barrel, and an engagement between the plunger rod and the engagement portion forces the main body portion to expand in the radial direction toward the inner wall of the syringe barrel, wherein the front attachment end of the syringe plunger body comprises an extension portion distinct from the radially extending member and extending in a longitudinal direction with respect to the longitudinal axis of the plunger rod and toward the closed front end of the stopper, said extension portion configured to contact a lower surface of the flexible roof during an injection to limit the expansion of the flexible roof in the radial direction. a) a substantially cylindrical syringe barrel comprising a fluid dispensing end and an open end; b) a stopper configured to be received within the open end of the syringe barrel, the stopper comprising: i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof, wherein the flexible roof is flat or the closed front end of the main body portion includes a first angled portion and a second angled portion forming a single conical surface that extends toward a tip providing the closed front end; and ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and i) a main body portion defining an open rearward end configured to receive a plunger rod, an engagement portion provided along an inner circumference of the main body portion, and a closed front end forming a flexible roof, wherein the flexible roof is flat or the closed front end of the main body portion includes a first angled portion and a second angled portion forming a single conical surface that extends toward a tip providing the closed front end; and ii) a first perimetrical skirt extending around an outer circumference of the main body portion toward the closed front end of the main body portion; and c) a plunger rod having a plunger rod body extending along a longitudinal axis, the plunger rod body comprising a front attachment end having a radially extending member configured to engage the engagement portion provided along the inner circumference of the main body portion of the stopper and a back end,