A separator tube adapted to be pushed into a collection tube containing {HEAD ~ blood} for separating serum or {TAIL ~ plasma} from the formed elements of the blood, said separator tube comprising: 
for separating
A separator tube adapted to be pushed into a collection tube containing { HEAD ~ blood } for separating serum or { TAIL ~ plasma } from the formed elements of the blood , said separator tube comprising :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH