{HEAD ~ The platelet rich plasma} is separated from {TAIL ~ the residual red blood cells} in a first part 
{ HEAD ~ The platelet rich plasma } is separated from { TAIL ~ the residual red blood cells } in a first part
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH