2. Composition of the blood
The circulating blood is composed of plasma
and cells.
The cells are red cells (or erythrocytes),
white cells (or leucocytes) and platelets.
Blood cells can be identified in blood films
stained with a mixture of basic and acidic
dyes.
Normal white cells are divided into
polymorphonuclear leucocytes (or
granulocytes) and mononuclear cells.
3. White blood cells
There are three types of
granulocyte named
according to their
staining characteristics
in blood films. They are
neutrophils,eosinophils
and basophils.
Mononuclear cells are
divided into
lymphocytes and
monocytes.
5. Band form Neutrophils
There are smaller
numbers of cells of
neutrophil lineage with
non-segmented nuclei.
They are referred to as
neutrophil band cells or
band forms. They are
less mature than
segmented neutrophils.
An increased number
of band cells is referred
to as a'left shift'.
9. Normal monocyte
Monocytes are the
largest WBC.
The nucleus is
slightly indented .
The cytoplasm is
abundant, sky blue
in colour.
Some have
vacuoles in the
cytoplasm.
10. Red cells
Normal red cells or
erythrocytes show
only slight variation
in size and shape.
The blood film
should be examined
in the area where
the red cells are
touching but not
often overlapping.
11. Red cells
. In this area many red
cells have an area of
central pallor which may
be up to a third of the
diameter of the cell. This
is consequent on the
shape of a normal red
cell, which resembles a
disc that is thinner in the
centre.
12. Platelets
Normal platelets are
also apparent. They
are small anuclear
fragments between
the red cells
containing small
purple-staining
granules.
13. Platelet ribbon
A string of platelets
or Platelet Ribbon.
This is the
appearance of normal
platelets when being
shed by a
megakaryocyte into
the marrow sinus.
The ribbon then
breaks up into
numerous small
platelet fragments.
Normal blood - 100X
14. Platelet aggregates
Platelet aggregates may
be
composed of apparently
intact
platelets, degranulated
pale grey platelets or a
mixture of both, as in this
example. If the platelet
count is low it is
essential to examine the
blood film carefully for
platelet aggregates.
15. Platelet satellitism
Platelet satellitism
describes the
phenomenon of
adherence of platelets to
white cells.
It is an in vitro
phenomenon of no
clinical significance.
However it is important
that it is detected since
the platelet count will be
factitiously low.
16. Nucleated epithelial cells
Extraneous non-
haemopoietic cells are
sometimes seen in blood
films. These include
epithelial cells which are
readily identified from
their abundant sky-blue
cytoplasm and small
central nucleus. They
are more often seen
if capillary blood is
obtained by
percutaneous puncture
than when a film is made
17. Endothelial cells
Endothelial cells are very
occasionally seen in
films prepared from
venous blood samples.
They have rather
pleomorphic oval nuclei
with a grooved surface.
The cytoplasm is scanty
and the cell outline is
irregular. They tend to
occur in clumps. It is
important not to confuse
normal endothelial cells
with carcinoma cells
which are also very
occasionally seen in the
18. Artefacts
Fixation artefact is the
term used for the
artefact that occurs
when there is water in
the methanol used for
fixation of the blood
film.This leads to
refractile rings in red
cells and makes it quite
impossible to assess red
cell morphology.
19. Heat artefact
Inadvertent heating of a
blood
sample, for example
during
transport in a hot car, can
lead to a heat artefact.
Red cells bud off
vesicles and
microspherocytes seen.
White cells disintegrate
and
proteins coagulate,
producing weakly
20. Storage artefact
Prolonged storage of blood
before making the blood film,
particularly storage at room
temperature,leads to storage
artefact.
White cells become fragile
and may form smear cells
[deep red arrow].
Neutrophil nuclei round up
and form homogeneous
round masses or a single
mass [blue arrow].These cells
have a resemblance to
NRBC.
Red cells undergo an
echinocytic change or