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