Final answer:
Red streaks within serum after centrifugation are known as fibrin strands, which occur as a result of the clotting process and subsequent fibrinolysis.
Step-by-step explanation:
Red streaks within serum after centrifuge is called fibrin strands. This occurs during coagulation, when fibrinogen is converted to fibrin, which forms a mesh that traps more platelets and erythrocytes, producing a clot. Over time, the stabilized clot undergoes fibrinolysis, where contractile proteins within the platelets contract and pull on the fibrin threads, tightening the clot and expelling out serum, which is the fluid part of blood without clotting factors. This process can leave behind strands of fibrin in the serum.