An antibody targeted to an antigen is brought into contact with {TAIL ~ a body component} in {HEAD ~ situ} 
An antibody targeted to an antigen is brought into contact with { TAIL ~ a body component } in { HEAD ~ situ }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD