150
UNIT 2
Basic Tissues
Promyelocyte
Eosinophilic
myelocyte
Eosinophilic
metamyelocyte
Eosinophil
Eosinophilic
stab cell
Neutrophil
Neutrophilic
myelocyte
Neutrophilic
metamyelocyte
Neutrophilic
stab cell
B
Figure 8-13B.
Overview of stages of granulocytes in development, bone marrow smear.
Wright stain,
3
1,569
These are examples of microphotographs that show various stages of
granulocyte maturation
in the
neutrophilic
and
eosinophilic series
.
Granulocytopoiesis
D. Cui
Neutrophilic
myelocyte
Neutrophilic
metamyelocyte
Neutrophilic
stab cell
Mature
neutrophil
Eosinophilic
myelocyte
Eosinophilic
metamyelocyte
Mature
eosinophil
Eosinophilic
stab cell
Basophilic
myelocyte
Basophilic
metamyelocyte
Mature
basophil
Basophilic
stab cell
Myeloblast
Promyelocyte
A
Figure 8-13A.
A representation of granulocytopoiesis.
In addition to
erythropoiesis
,
leukopoiesis
also occurs in the bone marrow. Here are examples of the development of
granular
leukocytes
(
granulocytopoiesis
). The
myeloblast
is the earliest morphologically recognizable precursor cell. Cell division occurs in
myeloblasts, promyelocytes, and myelocytes. The myelocyte is the last stage that is capable of dividing. The generation of nonspe-
ciF
c granules occurs in the promyelocyte stage and speciF
c granules in the myelocyte stage. Maturation of granulocytes follows
this sequence:
myeloblasts
,
promyelocytes
,
myelocytes
,
metamyelocytes
, and
stab (band) cells
. The following morphologic changes
occur during granulocyte maturation: (1)
nucleoli
are present only before and during the promyelocyte stage; (2) the nucleus takes
the following shapes in different developmental stages: oval, elongated, indented, arched, and then segmented (lobed); and (3)
spe-
ci±
c
granules
are F rst present at the myelocyte stage.
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