White blood cells or leukocytes are cells of the immune system which defend the body against both infectous disease and foreign materials.

The white blood cells have a rather short life cycle, living from a few days to a few weeks.

White cell count (WBC) is the total number of leukocytes in a volume of blood, expressed as thousands/µl.

Principle: Using diluent that destruct all blood cell leaving only WBCS intact

Equipment and reagents:

1. Hemacytometer and cover slip.

2. Glass pipette.

Reagents:

1. Turks' solution: which is formed of: Glacial acetic acid Gentian violet Distilled water.

Specimen:

EDTA- anticoagulated blood

Procedures:1. Blood dilution:Add 10 µl of well mixed blood sample to

200µl of the diluting reagent.The dilution factor is 1:20.2. leave the mix for 2 mins. till complete

lyses of RBCs.

2- Charging :

Charge the hemocytometer between couver slip and the counting chamber. Leave the cells to settle down.

3- Counting:

Count the WBCs in 4 1ry squares. Count in L- shape manner. Count under medium power.

????? Cell / 4 squares.

Leukocytes\ µl of blood =

No. of cells x depth factor x dilution factor =

no. of square counted

Leukocytosis is a condition characterized by an elevated number of white cells in the blood, which is usually due to:

Bacterial infection such as appendicitis, tonsillitis, ulcers and urinary tract infection

Leukemia. Following exercise. stress.

Leukopenia is a condition characterized by a decreased number of white cells in the blood, which is usually due to:

Viral disease such infectious hepatitis. Some bacterial infections such as

brucellosis. Radio therapy and chemotherapy.

In case of counting WBCs and RBCs in poultry or fish blood, one is preferred to use Natt and Herrick solution.