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