The discs may include inwardly directed notches formed in their outer perimeter, with the notches cooperating with {TAIL ~ an interior wall} of the housing to cut {HEAD ~ tissue} specimens 
The discs may include inwardly directed notches formed in their outer perimeter , with the notches cooperating with { TAIL ~ an interior wall } of the housing to cut { HEAD ~ tissue } specimens
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH