{HEAD ~ Some} of the first step antibody binds to {TAIL ~ antigens} present at or near the body part, and unbound first step antibody is washed away 
binds to
{ HEAD ~ Some } of the first step antibody binds to { TAIL ~ antigens } present at or near the body part , and unbound first step antibody is washed away
HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH