The device comprises a support sheath (14), a syringe body (10) secured to said sheath, and a protection sheath (16) movable between a retracted position and an extended protection position. The device includes retaining means (17) for retaining the protection sheath that are adapted to be urged so as to allow the sheath to be extended. The syringe body (10) is secured to the support sheath (14) via a ring (20) including a coupling wall (22) that is substantially transverse. This wall presents at least one slot (23) enabling the retaining means to be acted upon from the side of the coupling wall (22) that is opposite from the distal end of the support sheath.