The connector has a fixed axial end fitting (3) conformed such that an elastically deformable monoblock valve is maintained on the fitting. A slot of the valve has a molded proximal slit (9A) such that the slot is opened and closed when a closure (5a) is outside an axial duct (4) and laterally forced by a wall of the duct, respectively. A pierced distal slit (9B) allows communication between the proximal slit and a tubular space (6) when the slot is opened. The fitting traverses the distal slit and a part of the proximal slit when the closure is outside the duct, without penetrating slot.
