A separator tube for insertion into {HEAD ~ a collection tube} comprises {TAIL ~ a tubular member} having one end closed by a plug 
A separator tube for insertion into { HEAD ~ a collection tube } comprises { TAIL ~ a tubular member } having one end closed by a plug
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH