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