In a further preferred aspect of the present invention, {HEAD ~ the elongate penetrating element} is {TAIL ~ a needle}, having a retractable obturator at its distal end 
is
In a further preferred aspect of the present invention , { HEAD ~ the elongate penetrating element } is { TAIL ~ a needle } , having a retractable obturator at its distal end
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH