Blood and Bone Marrow
Histology SSN
November 18, 2004
Presented by:
Nadia Goodwin & Missy Walker
Formed Elements of the Blood
Peripheral Blood: Erythrocytes
• RBCs constitute the
largest number of cells
in the blood
• Biconcave discs
• NO NUCLEUS
• Contain Hemoglobin
Peripheral Blood: Platelets
• Derived from
Megakaryocytes in
bone marrow – formed
from small bits of
Megakaryocyte
cytoplasm
• Function in blood
clotting
Peripheral Blood: Leukocytes
• GRANULOCYTES
– Neutrophils
– Basophils
– Eosinophils
• AGRANULOCYTES
– Lymphocytes (T and B cells)
– Monocytes (Macrophages)
Peripheral Blood: Leukocytes
• GRANULOCYTES
– Neutrophils
– Basophils
– Eosinophils
Granulocytes: Neutrophils
• Most numerous WBC in
blood
• Multilobed nucleus
• Granules:
– Azurophilic granules
– Specific granules
• Function
– 1st wave of cells in acute
inflammation; can
phagocytose bacteria
Granulocytes: Basophils
• Rare!
• Lobulated nucleus often
obscured by granules
• Dark Blue Granules
– Hydrolytic enzymes,
heparin sulfate, histamine,
SRS
• Function
– Role in hypersensitivity and
anaphylaxis
Granulocytes: Eosinophils
• Bilobed nucleus
• Bright pink Granules
– Arginine rich major basic
protein, peroxidase,
histaminase, arylsulfatase
• Function:
– Important in allergic rxns,
parasitic infections, and
phagocytosis of Ab-Ag
complexes
Agranulocytes: Monocytes
• Largest WBCs in
blood smear
• Migrate through blood
to the tissues; once in
tissues they
differentiate into
phagocytes
(macrophages)
Agranulocytes: Lymphocytes
• About size of RBCs
• Function
– Main functional cells
of adaptive immune
system
– T cells
– B cells
Questions
Which of the following cell types would be expected to be increased in
number with a bacterial infection? Viral? Parasitic?
RBC Development
Watch for trends!
Proerythroblast
• Biggest in lineage
• Large central nucleus
with one or two
nucleoli
• Basophilic cytoplasm
b/c ribosomes
• Look for Golgi ghost
Basophilic Erythroblast
• Smaller than
proerythroblast
• Checkerboard nucleus
(heterochromatic)
• Intense basophilia
(lots of ribosomes!)
Proerythroblast vs Basophilic Erythroblast
Polychromatophilic Erythroblast
• Smaller than basophilic
erythroblast
• Smaller intensely
heterochromatic nucleus
• Purple/lilac cytoplasm mix
of basophilia from
ribosomes and growing
eosinophilia from
hemoglobin
• LAST MITOTIC STAGE!
Normoblast
• Smaller than
polychromatophilic
erythroblast
• Small, compact,
intensely staining
nucleus that is getting
ready to be extruded
• Eosinophilic
cytoplasm due to
abundant hemoglobin
Reticulocyte
• Immature RBC that
has polyribosomes
• Appear as polychromatophilic erythrocyte
on blood smear
• When stained with a
special (supravital)
stain  Reticulocyte
Erythrocyte
• Smallest
• Eosinophilic due to
hemoglobin
• NO NUCLEUS!
Erythropoiesis
Development of Granulocytes
What are the Granulocytes?
These are cells of the immune system (White Blood Cells)
that contain vesicles. The vesicle contents vary among
cell lines and stain differently.
• Neutrophils (polymorphonuclear or PMN cells)
• Eosinophils
• Basophils
Trend of Development
• Larger to smaller
• Azure granules to specific granules
• Round nucleus to altered shape nucleus
Granulocyte Lineage:
Myeloblast → Promyelocyte → Myelocyte →
Metamyelocyte → Band → Granulocyte
(Erythroid: Proerythroblast →Basophilic erythroblast → Polychromatophilic
erythroblast → Normoblast → Reticulocyte → Erythrocyte)
Myeloblast
Prominent
nucleoli
PROmyelocyte
• Details
• Golgi ghost
• Can’t distinguish type
of granulocyte yet
• Eccentric nucleus
• Don’t confuse with
proerythroblast or
basophilic erythroblasts
Myelocyte
• Last stage in
which
mitosis can
occur
• Begin to see
who’s a
neutrophil,
who’s an
eosinophil
(who’s a
basophil)
• Golgi ghost
Neutrophilic Myelocyte vs
Eosinophilic Myelocyte
METAmyelocyte
• nucleus changing
shape, not spherical
• Soooo . . . No more
mitosis
Band Cell
• Immature granulocyte
• Elongated nucleus of
nearly uniform width;
horseshoe/U-shaped
Finally . . .
Myeloblast – no granules
capable of
mitosis
Promyelocyte – azurophilic granules
Mylocyte – specific granules
Metamylocyte – specifc granules
nucleus
changes shape
Band cell – (PMN only) specific granules
Mature Granulocyte – specific granules
Compare what you see . . .
Megakaryocyte
• Huge
• Platelets form
from
invaginations
of this
• Multilobular
nucleus
Megakaryocyte
Don’t Worry, Be Happy!