{HEAD ~ The outer peripheral cell wall} includes an outermost peripheral cell wall forming part of {TAIL ~ the outer peripheral surface} of the block 
{ HEAD ~ The outer peripheral cell wall } includes an outermost peripheral cell wall forming part of { TAIL ~ the outer peripheral surface } of the block
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH