Final answer:
The buffy coat in a centrifuged hematocrit tube is a thin, pale layer that consists of leukocytes (white blood cells) and platelets.
Step-by-step explanation:
The buffy coat in a spun hematocrit tube consists of WBCs and platelets. These are the leukocytes (WBCs) and the platelets (cell fragments also called thrombocytes), which form a thin, pale layer separating the erythrocytes (red blood cells) from the plasma. The buffy coat typically makes up less than 1 percent of a centrifuged blood sample. Red blood cells settle at the bottom of the hematocrit tube due to their weight, and the plasma, which contains various substances necessary for bodily functions, forms the topmost layer of the centrifuged sample.