{HEAD ~ a valve seating portion} having {TAIL ~ a valve opening} therein, said valve opening permitting serum or plasma to flow into said tubular member when the separator tube is plunged into the collection tube, 
having
{ HEAD ~ a valve seating portion } having { TAIL ~ a valve opening } therein , said valve opening permitting serum or plasma to flow into said tubular member when the separator tube is plunged into the collection tube ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH