III.  Platelets count (Thrombocytes count)


Sodium citrate

3.8 g

Formaldhyde (40 %)

0.2 ml

Brillient cresyl blue

0.1 g

Distilled water

100 ml






I- Filling the pipette

  1. Diluting fluid is drawn to the mark 1 of the RBC pipette and immediatelly expelled.

  2. Aspirate blood to 0.5 mark of the RBCs diluting pipette.

  3. Aspirate diluting fluid  to 101 mark.

  4. Mix blood and diluting fluid mechanically for 5 min.

II- Filling the counting chamber:

  1. Proceed as previously explained in RBCs count.

  2. Allow counting chamber to stand for 20-30 minutes to allow the platelets to settle.

  3. To prevent drying out of the preparation, it showed be kept in a moist atmosphere, this is most easily arranged by placing the filled counting chamber in the bottom of a clean Petri dish, along side of which arrange a small piece of cotton wool which has been soaked in water and squeezed out. Petri dish lid is additionally put over the dish.

  4. After 20 -30m the counting chamber can be removed and carefully transferred to the microscope stage.

III- Counting the number of platelets


X 200

= 1000