CHAPTER 8
Blood and Hemopoiesis
141
Figure 8-5A.
Neutrophils, blood smear.
Wright
stain,
3
754; inset
3
1,569
Neutrophils
are the most abundant cells in the leu-
kocyte series. They have a multilobed (two to f
ve
interconnected lobes) nucleus and pale pink cyto-
plasm with many granules (or
vesicles
). There are
two main types oF granules in neutrophils:
primary
(
nonspecif
c
) and
secondary
(
specif c
)
granules
.
Primary granules
are azurophilic granules, which
are modif
ed
lysosomes
. The neutrophils’ primary
granules are larger and less numerous than specif
c
granules.
Secondary granules
(
specif c
or
neutro-
philic
granules
) are more numerous than primary
granules, and they contain a variety oF antibacterial
compounds. They stain lavender or salmon-pink
with Wright stain, but they are diFf cult to distin-
guish because oF their small size. Like other
granular
leukocytes, neutrophils are terminally diFFerentiated
cells unable to divide. They play a primary role in
deFense against bacterial and Fungal inFections.
D. Cui
Neutrophils
Neutrophilic
stab (band)
cell
Lymphocyte
Neutrophil
A
Neutrophilic granules
Neutrophilic granules
Lobes of nucleus
Lobes of nucleus
Capillary endothelium
Capillary endothelium
Neutrophilic granules
Lobes of nucleus
Capillary endothelium
B
Figure 8-5B.
Neutrophil in a capillary.
EM,
3
11,000
This
leukocyte
f lls the lumen oF the
capillary
in which it resides. Although the thickness oF the section is only about one
two-hundredth oF the diameter oF the cell, the Features oF the neutrophil are readily apparent. Prof
les oF three
lobes o± the nucleus
can be seen, and the cytoplasm has an abundance oF small granules that vary in electron density. The shapes oF the granules also
vary From spherical to rice shaped. It is diFf cult to unequivocally distinguish the two main types oF granules strictly on the basis
oF morphology. However, the smallest and most numerous granules are
specif
c
(
neutrophilic
,
secondary
)
granules
, and the largest
granules are
nonspecif c
(
azurophilic
,
primary
)
granules
. The neutrophilic granules are diFf
cult to discern in the light microscope
because their size is close to the limit oF resolution oF light microscopy.
Leukocytes: Granulocytes
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