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Blood Cells and Hemopoiesis
SEM of a neutrophil (purple) ingesting S. aureus bacteria (yellow). NIAID.
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Blood
1. Blood is a specialized type of fluid connective
tissue that provides the body’s tissues with
nutrition, oxygen, and waste removal and serves
as a means of transportation for the activity of
other body systems (e.g., carrying hormones
from source to target for the endocrine system).
2. It consists of plasma (liquid ECM of blood) and
formed elements (cells and platelets).
3. The “formed elements” of blood derive from
hematopoietic stem cells located in the red bone
marrow of flat bones in adults.
4. Blood cells can be classified as red blood cells
(about 45% of blood) and white blood cells
(about 1% of blood) based upon their gross
appearance upon centrifugation.
5. White blood cells ( leukocytes ) can be further
classified as granulocytes (neutrophils, basophils,
eosinophils) or agranulocytes (monocytes and
lymphocytes) based upon the presence of
absence of cytoplasmic secretory granules.
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Identifying “Formed Elements”
Since some “blood cells” are not actually cells when functional, the term “formed elements” is
often used to describe the “cellular” content of blood. When evaluating the formed elements
of blood, there are several characteristics to keep in mind when attempting to identify the
type of “cell”:
1. Location the sample was taken from (if known)
2. Size of the element
3. Nucleus to cytoplasm volume ratio (N:C)
4. Number and shape of nuclei
5. Degree of chromatin condensation
6. Presence or absence of nucleoli
7. Cytoplasmic staining
8. Presence and staining of cytoplasmic granules
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Learning Objectives
- Understand that blood is a connective tissue with “formed elements” (cells and platelets) in a fluid matrix (plasma).
- Understand the morphology and function of red blood cells (erythrocytes) and the role of the spectrin membrane skeleton in maintaining their biconcave shape and flexibility.
- Understand the relative numbers of the various types of white blood cells in the blood of normal adults and know the major functions of each type.
- Understand that all leukocytes display cell motility and function in secretion, phagocytosis, etc. primarily in the ECM of tissues after migrating across the blood vessel wall (diapedesis).
- Be able to recognize and find neutrophils, eosinophils, basophils, monocytes, and platelets in a blood smear.
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Keywords
Basophil
Bone marrow
Eosinophil
Erythrocytes
Hemopoiesis
Hemopoietic cord
Leukocytes
Lymphocyte
Megakaryocyte
Metamyelocytes
Monocyte
Myelocytes
Neutrophil
Normoblasts
Platelets
Proerythroblasts
Red blood cells
Red marrow
Reticulocytes
Sinusoids
Stab cells
Stromal cells
Thrombocytes
White blood cells
Yellow marrow
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Slide 35a (NW): Blood Smear
Slide 23 (464): Blood Smear, Wright’s
zoom in to identify leukocytes (white blood cells)
amongst all the erythrocytes (red blood cells)
Slide 10: Blood Smear, Wright’s
notice the difference in staining of the RBCs on
the three blood smear slides; use the coloration
of the acidophilic RBCs as a reference in
identifying other cell types (e.g., eosinophils)
Slide 10: Blood Smear, Wright’s stain
% of WBCs 40-75%
Diameter 10-15 μm
N:C 1:
Nucleus Multi-lobed in a variety of shapes Chromatin Condensed
Nucleoli No
Cytoplasm Non-distinct staining of granules
neutrophils ( polymorphonuclear neutrophils , polymorphs , or segmented neutrophils ) are the most
abundant type of leukocyte with approximately 10^11 leaving the bone marrow each day; they circulate for 6-
10 hours before exiting into the tissues where they live for 1-2 days; like most mature leukocytes, they have
condensed chromatin and few cytoplasmic organelles; they are phagocytic and the first-responders at sites
of inflammation to destroy damaged tissue and bacteria
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Slide 35a (NW): Blood Smear, Wright’s stain
band cells are the final stage of all granulocyte development before becoming mature cells but are usually
only seen for neutrophils; they generally have a characteristic “horseshoe”-shaped nucleus, instead of the
segmented (“string of sausages”) nucleus of mature neutrophils; they are normally only seen in low
numbers in the peripheral circulation but may become more numerous during inflammation or infection;
this increase is referred to as a “left-shift” (etymology of the term is uncertain) or bandemia
% of WBCs < 5 %
Diameter 10-15 μm
N:C 1:
Nucleus “Horseshoe”
Chromatin Condensed
Nucleoli No
Cytoplasm Non-distinct staining
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
% of WBCs < 1%
Diameter 14-16 μm
N:C 1:
Nucleus Bi-lobed (if seen)
Chromatin Condensed
Nucleoli No
Cytoplasm Large, basophilic granules that often obscure everything else in the cell
basophils are granulocytes and the rarest type of circulating leukocyte; they appear similar to mast cells
(only in tissues) with a bi-lobed nucleus that is usually obscured by the numerous, large, strongly-basophilic
granules that fill the cytoplasm; basophils play a role in parasitic infections and are part of the inflammatory
response (contain histamine and heparin); a neutrophil can be seen in the lower left of the slide
Slide 23 (464): Blood Smear, Wright’s stain
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Slide 10: Blood Smear, Wright’s stain
% of WBCs 20-50%
Diameter 6-12 μm (90%) 15-20 μm (10%)
N:C 4:1 (small cells) 2:1 (large cells)
Nucleus Large, spherical
Chromatin Condensed
Nucleoli No (until activated)
Cytoplasm Minimal and basophilic; Golgi is usually visible
lymphocytes are agranulocytes generally similar in size to RBCs but have a very large, round nucleus which
fills most of the cell, leaving little cytoplasm with few organelles; the cells function as part of the adaptive
immune system but specific subtypes (B and T cells) are not distinguishable in light microscopy (majority
are T cells, however); activated lymphocytes may enlarge and appear similar to monocytes but are still
distinguishable by their nuclei
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Slide 10: Blood Smear, Wright’s stain
Diameter 1-3 μm
N:C --
Nucleus --
Chromatin --
Nucleoli --
Cytoplasm Basophilic
Granulocyte? --
platelets are small cellular fragments derived from megakaryocytes in the bone marrow; when in contact
with collagen (exposed CT), platelets adhere and degranulate, triggering the formation of a blood clot;
around 10^11 platelets are produced each day in a healthy adult, and they survive in the circulation for 7-
days
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Slide 104: Bone, H&E
yellow (er) bone marrow
(less hematopoietically active)
by adulthood, 85% adipose tissue
found in medullary cavity (trabecular bone) of long
bones
Slide 34: Bone, H&E
red bone marrow
(more hematopoietically active)
by adulthood, 40% adipose tissue
found in flat bones and trabecular bone near
epiphysis of long bones
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
trabecula of bone
hemopoietic cord
with clusters of blood cell
precursors and megakaryocytes
“spaces” are adipocytes
Slide 153: Bone Marrow, Needle Biopsy, H&E
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
Slide 20a (464): Bone Marrow, H&E
sinusoids
adipocyte
hemopoietic
cord
IUSM – 2016
I. Introduction
II. Learning Objectives
III. Keywords
IV. Slides
A. Blood Cells
- Erythrocytes (Red Blood Cells)
- Leukocytes (White Blood Cells) a. Granulocytes (PMNs) i. Neutrophils ii. Eosinophils iii. Basophils b. Agranulocytes (Mononuclear) i. Lymphocytes ii. Monocytes
- Thrombocytes (Platelets) B. Bone Marrow
- General structure
- Cells a. Megakaryocytes b. Hemopoietic cells i. Erythroid precursors ii. Myeloid precursors
V. Summary
