Next, {HEAD ~ cells} are inoculated with neurotropic virus under conditions that restrict {TAIL ~ viral propagation} 
Next , { HEAD ~ cells } are inoculated with neurotropic virus under conditions that restrict { TAIL ~ viral propagation }
OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL