Platelets are one of the formed elements in the blood of mammals. They are small, biologically active cytoplasmic fragments shed from the cytoplasm of mature megakaryocytes in the bone marrow through lysis. Platelets possess a specific morphological structure and biochemical composition, and play a crucial role in physiological and pathological processes such as hemostasis, wound healing, inflammatory response, thrombosis, and organ transplant rejection.
Platelet Diluent is a type of solution that can lyse red blood cells in the blood while preserving the intact morphology of platelets. It is used to dilute blood samples, which are then loaded into a hemocytometer for the direct counting of platelets under a high-power microscope. This platelet diluent is for research use only and not intended for clinical diagnosis or any other applications.
Operating Procedures (For Reference Only):
1. Take a small test tube and add 0.38 mL of platelet diluent to it.
2. Use a clean, dry micropipette to draw 20 μL of capillary blood. Wipe off excess blood from the outside of the pipette, add the blood to the platelet diluent, aspirate the supernatant gently three times, and mix the solution thoroughly immediately.
3. After complete hemolysis, mix the solution again for 1 minute. Take one drop of the well-mixed platelet suspension and load it into the hemocytometer, taking care to avoid bubble formation or overflow. Let it stand at room temperature for 10–15 minutes to allow platelets to settle completely.
4. Place the hemocytometer under the high-power microscope of a light microscope, and count the number of platelets in five medium squares in total—i.e., the four corner medium squares and the central medium square within the large central counting square—one by one.
Calculation:
Platelet count/L = Number of platelets in 5 medium squares × 10⁹/L
Precautions:
1. The needle puncture should be slightly deep. After wiping off the first drop of blood, collect blood for platelet counting first. Perform all operations rapidly to prevent platelet aggregation.
2. Complete platelet counting within 1 hour after blood collection to avoid interfering with the test results.
3. Ensure the small test tubes and hemocytometers are thoroughly clean to prevent misidentification of foreign particles as platelets.
4. Use moderate light during counting, and take care to distinguish refractive platelets from impurities.
5. Counting with a phase-contrast microscope yields better and more accurate results.
6. For your safety and health, wear a lab coat and disposable gloves during all operations.
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