Male Hartley guinea pigs from Charles River, weighing 250 275 grams on arrival and 300 600 grams at testing, serve as {HEAD ~ subjects} in {TAIL ~ the experiment} 
Male Hartley guinea pigs from Charles River , weighing 250 275 grams on arrival and 300 600 grams at testing , serve as { HEAD ~ subjects } in { TAIL ~ the experiment }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL