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.

Granulocytes

( segmented)

Agranulocytes(nonsegmented)

Basophil

Eosinophil

Neutrophil

Monocyte

lymphocyte

Neutrophile• Nucleus is segmented (3-5 segments).• Has dust like granules.• In poultry called Heterophile

( Pseudoesinophile)o which has granules in the form of Red-rod

shape granule

Mammalian Equine

nucleus (3-5 segments). basophilic granules, that masking the

nucleus.

1- Lymphocyte : Small & Large lymphocytes. Nucleus occupy most size of the cell,

leaving thin rim of cytoplasm. chromatin is of condensed type ( dark

stained)

2- Monocyte :• Large size cell• Kidney shape or irregular nucleus • Chromatine of the nucleus has thready appearance.• Cytoplasm contain lysozymes ( cytoplasmic vacules).

• toxic change in neutrophils is not necessarily associated with "toxemia". • The term derives from the fact that these abnormalities were first noticed in human patients with gram negative sepsis and endotoxemia. • However, toxic change in neutrophils do not reflect a "toxic effect" of bacteria on neutrophils but are morphologic abnormalities acquired during maturation under conditions that intensely stimulate neutrophil production and shorten the maturation time in marrow. •This accelerated maturation occurs secondary to cytokine stimulation, which is usually in reponse to inflammation. 

Signs of toxic changes ( or accellerated maturation):-Signs of toxic changes ( or accellerated maturation):-

 the cells retain immature features, including increased amounts of rough endoplasmic reticulum or ribosomes in the cytoplasm.

lighter chromatin than normal.

Specific granules may be less visible than in normally mature cells and, in some species, primary granules (normally inapparent in neutrophils) retain their staining affinity for the stains used for peripheral blood.

The cells can also have frothy or vacuolated cytoplasm.

• Dohle bodies,

Diffuse basophilia

• Cytoplasmic foaminess

• Toxic granulation

bluish, angular cytoplasmic inclusion, Located at the periphery of cytoplasm of neutrophils. representing retained aggregates of rough endoplasmic reticulum. The earliest and first indication of toxic change. Dohle bodies form in neutrophils with storage (storage-related artifact),

so Dohle bodies alone do not always indicate toxic change.  healthy cats can have low numbers of small Dohle bodies.

diffuse irregular blue appearance to the cytoplasm.

Due to the presence of polyribosomes and rough endoplasmic reticulum.

Can be seen during bacteremia and generalized infection .

These are indistinct vacuoles in the cytoplasm, giving it a frothy appearance

Due to degranulation of lysosomes, which result in autodigesion.

Appear in sever inflammation.

Characterized by prominent purblish cytoplasmic granules.

1ry granules retain their staining affenity. most commonly seen in large animals

(horses, ruminants, camelids ). it’s presence suggest sever inflammatory

process.

Band cell

Hypersegmentation

Giant hypersegmentation

Band neutrophilHypersegmented neutrophil(>5 segments)

Normal neutrophil(3-5 segments)

Shift to left(Inflammation)

Shift to right(Aging)

Occurs in vitamin B12 and folic acid deficiency (Megaloblastic anemia)