A ring applied to {HEAD ~ the surface} of {TAIL ~ the tissue} stabilizes the tissue to the optics and localizes a portion of the tissue surface through an aperture in the ring 
A ring applied to { HEAD ~ the surface } of { TAIL ~ the tissue } stabilizes the tissue to the optics and localizes a portion of the tissue surface through an aperture in the ring
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH