The gel separator in an evacuated blood collection tube serves a crucial role in the separation of blood components. When blood is drawn into the tube, the gel creates a physical barrier after centrifugation, which allows for the separation of the components based on their density.
In particular, when a tube containing a gel separator is centrifuged, the gel moves to the interface between the red blood cells (RBCs) and the plasma. This separation happens because RBCs are denser and settle at the bottom of the tube, while the plasma, which contains various components including proteins, electrolytes, and hormones, remains above the gel layer. White blood cells (WBCs) and platelets also settle within the buffy coat, which is a thin layer found between the plasma and the RBCs.
By this method, the components can be easily accessed for further testing without the need for additional procedures to separate them, streamlining the laboratory workflow. Thus, the gel separator effectively allows for the clear distinction and collection of RBCs and WBCs from plasma and serum, as indicated by the correct choice.