A separator tube adapted to be pushed into {HEAD ~ a collection tube} containing blood for separating serum or plasma from {TAIL ~ 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 plasma from { TAIL ~ 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 OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH