Tissue is imaged by a microscope capable of {HEAD ~ imaging sections} of the tissue below {TAIL ~ the exposed tissue surface} through optics 
Tissue is imaged by a microscope capable of { HEAD ~ imaging sections } of the tissue below { TAIL ~ the exposed tissue surface } through optics
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH