BLOOD AND

BONE MARROW

DR.LOPEZ
 BLOOD
• specialized connective tissue
• consists of cells and fluid
extracellular material called
plasma
• three major cell types:
– erythrocytes (red blood
cells)
– leukocytes (white blood
cells)
– platelets
(thrombocytes)
PREPARING A BLOOD SMEAR
 BLOOD CELLS
• Erythrocytes or red
blood cells

– most numerous blood

cells
– nonnucleated cells
– biconcave shape that
provides a large surface-
to-volume ratio and
facilitates gas exchange
– 7.5 μm in diameter
Erythrocytes or red blood cells

• densely filled with hemoglobin

• central pale area

• life span: 120 days

• F: 3.9-5.5 million per microliter (μL,

or mm3)

• M: 4.1-6.0 million/μL
BLOOD CELLS

Leukocytes or white
blood cells

▪ N: 4500-11,000
leukocytes per microliter
of blood
▪ Function:defend the
body against bacterial
invasion or the presence
of foreign material
Neutrophils (Polymorphonuclear
Leukocytes)

• 50%-70% of circulating
leukocytes
• 12-15 μm in diameter
• nuclei having two to five lobes
linked by thin nuclear
extensions
Neutrophils (Polymorphonuclear
Leukocytes)
• short life span
• active phagocytes
• main types of cytoplasmic granules
of neutrophils:

– Azurophilic primary granules

– Specific secondary granules
 Eosinophils

• constitute 1%-4% of leukocytes

• about the same size as a neutrophil or

slightly larger, but with a characteristic
bilobed nucleus

• Main identifying characteristic

– distinct, large, eosinophilic (bright
pink or orange) granules
• contain major basic protein
– kill parasitic worms or helminths
 Eosinophils

• short life span

• phagocytic cells with a

particular affinity for
antigen–antibody
complexes that are formed
in the tissues in allergic
conditions
 Basophils
• <1% of circulating leukocytes

• not phagocytic

• 12-15 μm in diameter

• nucleus has two irregular lobes

• coarse purple granules

– contain histamine and heparin
 Lymphocytes

• constitute 20 to 30% of the

blood leukocyte

• most numerous type of

agranulocyte

• vary in size from cells smaller

than erythrocytes to cells
almost twice as large
Lymphocytes
 Lymphocytes
• variable life span, from days to
months

• essential for immunologic

defense of the organism

• some lymphocytes (B
lymphocytes), differentiate
into plasma cells in the
connective tissue and produce
antibodies
 Monocytes
• constitute y 3 to 8% of the blood
leukocytes

• largest agranular leukocytes (12-15 μm

diameter)

• nucleus is usually indented or

horseshoe-shaped

• chromatin is less condensed and

typically lighter

• abundant cytoplasm is lightly basophilic

 Monocytes
• precursors of the mononuclear
phagocyte system

• live in the blood for 2 to 3 days,

after which they move into the
connective tissue

• monocytes become powerful

phagocytes

• at the site of infection,

monocytes differentiate into
tissue macrophages
 BLOOD CELLS
Platelets (Thrombocytes)
• smallest of the formed elements (2-4 μm
in diameter)

• cytoplasmic remnants of
megakaryocytes

• irregular masses of basophilic (blue)

cytoplasm

• 150,000 to 400,000/μL (mm3) of blood

• promote blood clotting

Platelets (Thrombocytes)
• lightly stained hyalomere region

• darkly stained central granulomere

– alpha granules
• Contain platelet-derived growth
factor (PDGF), platelet factor 4

– delta granules
• contain ADP, ATP, and serotonin
(5-hydroxytryptamine)
 BONE MARROW

• Red bone marrow

– active in hemopoiesis
(blood cell formation)

• Yellow bone marrow

– consists mostly of
adipose tissue
BONE MARROW SPECIMEN COLLECTION
SITES
• Posterior superior iliac crest of
the pelvis
– provides adequate red marrow
that is isolated from anatomic
structures that are subject to
injury

• Anterior medial surface of the tibia

– in children younger than age 2
Criteria Used in Identification of Erythroid
Precursors
• As erythroid precursors mature,

1. Overall diameter of the cell decreases

2. Diameter of the nucleus decreases more

rapidly than does the diameter of the cell

3. Nuclear chromatin pattern becomes coarser,

clumped, and condensed.
Criteria Used in Identification of Erythroid
Precursors

4. Nucleoli disappear.

5. Cytoplasm changes from blue to gray-

blue to salmon pink.
ERYTHROCYTIC SERIES IN NORMAL BONE
MARROW
PRONORMOBLAST (RUBRIBLAST)

• Proerythroblast

• Nucleus
– N:C ratio of 8:1
– round to oval, containing one or
two nucleoli
– purple red chromatin is open and
contains few, if any, fine clumps

• Cytoplasm
– dark blue because of the
concentration of ribosomes and RNA
 BASOPHILIC NORMOBLAST
(PRORUBRICYTE)
• Basophilic erythroblast
• 10-15 um
• Nucleus
– N:C ratio 6:1
– more condensed nucleus
– nucleoli may be present early in the stage
but disappear later
– chromatin stains deep purple-red
• Cytoplasm
– dark blue (may be deeper, richer blue than
pronormoblast)
 POLYCHROMATIC
(POLYCHROMATOPHILIC) NORMOBLAST

• Rubricyte/Polychromatic erythroblast
• most numerous representatives of the
erythroblast series
• 10-12 um
• Nucleus
– chromatin pattern varies during this
stage of development, showing some
openness early in the stage but
becoming condensed by the end
– N:C ratio decreases from 4:1 to about
1:1 by the end of the stage
– no nucleoli
 POLYCHROMATIC
(POLYCHROMATOPHILIC) NORMOBLAST

• Cytoplasm
– hemoglobin synthesis starts
– color produced is a mixture of pink and
blue, resulting in a murky gray-blue

• last stage in which the cell is capable

of undergoing mitosis
 ORTHOCHROMIC NORMOBLAST
• Metarubricyte / Orthochromatic
erythroblast

• 8-10 um

• Nucleus

– completely condensed (i.e., pyknotic)-

N:C ratio is low or approximately 1:2

• Cytoplasm
– increase in the salmon pink color of
the cytoplasm reflects nearly complete
hemoglobin production
 POLYCHROMATIC
(POLYCHROMATOPHILIC)
ERYTHROCYTE OR RETICULOCYTE
• no nucleus

• predominant color is that of hemoglobin

yet with a bluish tinge
•
• larger than a mature cell, lacks central
pallor

• resides in the bone marrow for about 1

to 2 days and then moves into the
peripheral blood for about 1 day before
reaching maturity
 POLYCHROMATIC
(POLYCHROMATOPHILIC)
ERYTHROCYTE OR RETICULOCYTE

• small amount of residual ribosomal

RNA is present and visualized with a
supravital stain (new methylene
blue)

– appear as a mesh of small blue

strands, a reticulum,or merely blue
dots
AFTER LOSING THE RIBOSOMES, THE RETICULOCYTE BECOMES A MATURE
ERYTHROCYTE.
GRANULOCYTIC SERIES IN NORMAL BONE
MARROW
 MYELOBLASTS
• 0% to 3% of the nucleated cells in the
bone marrow

• 14 to 20 um in diameter

• Nucleus
– delicate, lace-like chromatin structure
– 2-5 nucleoli brighter than the
surroundings, in contrast to
proerythroblasts

• Cytoplasm
– scanty and stains blue (lighter than
proerythroblasts)
 PROMYELOCYTES
• comprise 1% to 5% of the nucleated cells in
the bone marrow
• larger than the myeloblast cells -16 to 25
um in diameter
• Nucleus
– round to oval and often eccentric
– chromatin structure is delicate
– one to three nucleoli but may be obscured
by the granules

• Cytoplasm
– evenly basophilic and full of primary
(azurophilic) granules
NEUTROPHIL MYELOCYTE
• smaller than promyelocytes-12-20 um
• Nucleus
– smaller but still round
– chromatin is condensed
– no nucleolus
• Cytoplasm
– bluish but turns pink as the cell matures

• final stage in which cell division (mitosis)

occurs

• Scattered fine neutrophil secondary

(specific granules) are found
 EOSINOPHIL MYELOCYTE

• slightly large than neutrophil

myelocytes (about 16 um)
• nucleus is round
• chromatin is condensed
• no nucleolus

• cytoplasm filled with orange-red

large uniform eosinophilic
(secondary granules-contain the
major basic protein)
 NEUTROPHIL METAMYELOCYTES
• 3% to 20% of nucleated marrow cells
• no longer capable of division
• slightly smaller than that of the myelocyte (14 to 16
um)
• synthesis of tertiary granules (also known as
gelatinase granules) may begin during this stage

• Nucleus
– indented (kidney bean shaped)
– chromatin is increasingly clumped
– nucleoli are absent

• Cytoplasm
– contains very little residual ribonucleic acid (RNA)
and therefore little or no basophilia
 EOSINOPHIL
METAMYELOCYTE
 BANDS
• 9%-32% of nucleated marrow cells and 0% -
5% of the nucleated peripheral blood cells
• diameters twice that of erythrocytes (about
15 um)
• Cytoplasm
– contains fine granules staining lightly
purple
• Nucleus
– highly clumped chromatin
– nuclear indentation that began in the
metamyelocyte stage now exceeds one
half the diameter of the nucleus, but actual
segmentation has not yet occurred
EOSINOPHIL BAND
 MEGAKARYOCYTES

• platelet precursor cell

• 50 - 150 microns (largest normal

nucleated cell in marrow)

• multinucleated (polyploid nuclei which are

large and irregularly lobulated with coarse
chromatin)

• abundant light blue to pink cytoplasm with

numerous purple red or pink granules

• 2 to 10 megakaryocytes per low-power field

• DIFFERENTIAL COUNT (using oil
immersion)
– numbers of all cells and cell stages
observed after performing a differential
count on 300–1000 cells and comparing
results with reference intervals

• MYELOID-TO-ERYTHROID (M:E) RATIO

– calculated by dividing the number of
granulocytic cells, including mature
granulocytes, by the number of
nucleated erythroid cells
– N= 1.5:1-3.3:1