Platelet/Thrombocyte count
Principle
Platelet/thrombocyte count is very high, the blood is
therefore diluted 200 times, with appropriate diluting fluid and then the
stained cells are counted in a hemocytometer. 
Their number in undiluted blood can then be calculated.
Direct method
In this method, diluting fluid used in Reese-Ecker fluid.
Its different components have the following characteristics:
- Brilliant cresyl blue => Stains the platelets
 - Formalin => prevents fungal growth
 - Sodium citrate => makes the fluid isotonic with blood
 
Identification of platelets
- Small, membrane bounds, non-nucleated granular bodies.
 - Oval is disc-shaped with condensed cytoplasm in the center, giving the impression of the nucleus.
 - Possess an extreme surface insatiability and throughout long pseudopodia.
 - Rapidly stick to and spread around other platelets or objects like glass.
 
Procedure
- Filter the Reese-Ecker fluid through double filter paper and draw it in the RBC diluting pipette up to the mark 0.5.
 - Wipe the tip and then draw blood from a finger prick to the 0.5 marks so that the platelet solution reaches the mark 1.
 - Wipe the tip again and fill the pipette with platelet solution to the mark 101.
 - Mix the contents for 2 minutes.
 - Discard the 1st 3-4 drops and charge the counting chamber with the diluted blood.
 - Count the platelet in five groups of 16 squares each (as for RBC, see at).
 - Calculate their number in undiluted blood by following the same formula as for RBC counting (see at).
 

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