A syringe assembly comprising: a body comprising an open proximal end, a side wall having an inner surface that defines a fluid chamber for retaining fluid and having a first width in cross section and a needle chamber (125) for housing a needle cone assembly (140), the fluid chamber and the needle chamber (125) being divided by a barrier wall having a first opening that allows fluid communication between the fluid chamber and the chamber ( 125) needle； a needle cone assembly (140) disposed inside the needle chamber (125), the needle cone assembly (140) comprising a needle cone (142), a needle cannula (150) supported inside the cone (142) of the needle by a frangible connection, the needle cannula (150) being in fluid communication with the first opening and being pushed to move in a proximal direction； a piston rod (160) disposed inside the fluid chamber comprising a distal end, a proximal end, a stop disposed at the distal end of the piston rod (160) to form a fluid tight seal with the inner surface of the body and a body of the piston rod extending from the distal end to the proximal end； and a firing element (190) disposed inside the needle chamber (125), including the firing element (190) a proximal end (199) and an open distal end (191) to break the frangible connection of the assembly (140) of the needle cone after the application of a force directed distally towards the firing element (190) and causing the needle cannula (150) to retract and be retracted inside the firing element.Un conjunto de jeringa que comprende: un cuerpo que comprende un extremo proximal abierto, teniendo una pared lateral una superficie interior que define una cámara para fluido para retener fluido y que tiene una primera anchura en corte transversal y una cámara (125) de aguja para alojar un conjunto (140) de cono de la aguja, estando divididos la cámara para fluido y la cámara (125) de aguja por una pared barrera que tiene una primera abertura que permite la comunicación de fluido e
