The invention provides an injector device for delivering a pay load to a tissue, comprising a housing, a cannula defining a lumen and having a proximal end received in the housing and a distal end extending from the housing, a hollow needle comprising a distal end with a tip for piercing tissue, a shifter that shifts the needle from an extended position to a retracted position, and an actuator for advancing a pay load from an initial position to exit from the distal end of the cannula. In the extended position, the needle occupies at least part of the lumen of the cannula, and the distal end of the needle extends past the distal end of the cannula, and in the retracted position, the distal end of the needle is withdrawn from the lumen of the cannula sufficiently to permit a pay load to advance from an initial position through the distal end of the cannula.
