{HEAD ~ System} for marking the locations of imaged tissue with respect to {TAIL ~ the surface} of the tissue 
{ HEAD ~ System } for marking the locations of imaged tissue with respect to { TAIL ~ the surface } of the tissue
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH