Counting of total leukocyte (TLC)

 

Apparatus and reagents

  • Hemocytometer
  • Turk’s fluid
  • microscope
  • coverslip
  • Blood sample

WBC Pipette


·         It has ground conical tip and a fine-bored narrow glass stem graduated in tenths and bears marking 0.5, 1.0, and 11.

  1. The glass capillary tube widens into a bulb that contains a white bead.
  2. The bulb narrows again into a glass capillary tube and at this point, it is marked 11.
  3. A thin rubber tube with a the plastic mouthpiece is attached beyond this.
  4. The white bead helps in mixing the contents of the bulb and for quick identification of the WBC pipette.

The difference from RBC counting method


This technique is similar to that used for counting erythrocytes (see RBC at), with the following exceptions:

  1. Diluting fluid is Turk’s fluid instead of Hayem’s solution.
  2.  Dilution of the blood is 20 times instead of 200. 
  3. The number of WBC is counted in each of the four large 1 mm2 squares in the corners of the ruled area and the average count determined.
  4. Low power objective (10X) is used for counting.

Calculation


The following multiplication factor is used to calculate the number of WBC per cubic milliliter of blood.

Multiplication factor
  • The cells were diluted 20 times (X 20).
  • The counting chamber is 0.1 mm deep (X 10).
  • The average number of cells in 1 mm2 were counted (X 1).

        Multiplication factor         =     20  X  10  X  1   =  200

        WBC                                   = WBC counted X 200

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