{HEAD ~ A method} 8, wherein {TAIL ~ the washing medium} is the culture medium used in stage  
wherein
{ HEAD ~ A method } 8 , wherein { TAIL ~ the washing medium } is the culture medium used in stage
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH