Dr.Sidra Qaiser
Introduction:
 In the differential leucocyte count (DLC) the
percentage of each type of white blood cells in the
total leucocyte population is determined. Each type of
white cells, performs a different function in the battle
against infections and each type of infection yields a
different white cell picture in the blood. The
morphology and staining characteristics of each type
is peculiar and is responsible for the in specific typing.
Arneth Count
 The age of the neutrophils can be determined by the
number of lobes of its nucleus. The cells having less
number of lobes are younger whilst with more lobes
are relatively older. The maximum number of lobes is
five in general.
Requirements:
 Clean glass slides, microscope, pricking needle, cotton
swab, dropper, glass rod, cedar wood oil, blow pipe and
Leishman's stain comprising of
 Leishman’s powder = 0.15 gm
 Methyl alcohol (acetone free) = 100 cc
 This stain contains both basophilic and eosinophilics
(acidophilic) staining components and thus helps to
discriminate among the granules of the differential
leucocytes.
Procedure:
 Preparation of blood film
 Sterilize the pricking needle and finger pulp with spirit
swab and then prick the finger, discard the first drop
of blood. Now apply the slide inverted over the drop of
the blood on the finger so that some blood sticks to
the slide. With the help of spreader slide at an angle of
45° spread the blood drop quickly with a constant
movement to prepare a thin film. Allow the slide to
become dry in air. Prepare two or three blood film
slides.
Staining of blood film
 Place the slides on the glass rod stand and pour 20 -30
drops of leishman's stain to cover the slide having
blood film and allow for 2 minutes. Now add distilled
water in order to dilute it, avoid the spilling over.
 Now wait for 10 minutes. Gently blow through the
blow pipe for mixing of distilled water and Leishman's
stain. Extra Leishman's stain is now rinsed by pouring
the water slowly on the slide until the colour becomes
pink. Dry the slide in the air.
Counting for DLC
 Choose an area where the film is made quite clear. The
three parts of a blood film include head, body and tail.
The body of the film is the best area for cell-counting.
Place two drops of cedar wood oil over the slide The
slide is put under the oil immersion lens in contact
with cedar wood oil Now move the slide slowly forward
and backward from right to left for focusing and
identification of different types of WBCs Count at least
100 cells to determine the percentage of DLC.

Precautions:
 The blood film should be thin and smooth.
 The slides used must be clean.
 The staining and blowing should be as gentle as
possible.
 The lens and slide contact must be carefully guarded
to avoid the breaking of slides.