The path through the shell wall may release {HEAD ~ a substance} contained in {TAIL ~ the shell} or allow a substance to enter the shell 
contained in
The path through the shell wall may release { HEAD ~ a substance } contained in { TAIL ~ the shell } or allow a substance to enter the shell
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH