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1. Blood
By:
Mohamed Abdelazim
MBBS OIU 2018

2. Why are we studying blood histology ?

3. Intended Learning Outcomes:
By the end of the lecture audience should be able to:
1- Define blood as a tissue.
2- List components of blood.
5- Recognize all of the cellular components found in
peripheral blood.
3- Memorize the functions of major plasma proteins and of the
different kinds of cells.
4- Memorize the abundance of various blood cells.

4. Definition of blood:
- It’s a specialized connective tissue
consisting of cells and fluid extracellular
material called plasma.

5. Blood preparation:
- Collected blood in which clotting is prevented by
addition of anticoagulants, can be separated to
three layers by centrifugation according to the
heterogeneity.
- Blood cells histology can be studied in smears
stained by eosin (acidic) and methylene
blue (basic).

6. FIGURE 1: Composition of blood.

7. 1-Plasma
- It’s an aqueous solution, pH 7.4,
containing substances of low molecular
weight that make up 7% of the volume
and the rest is water.

8. Composition of blood plasma:.
1- Water (92%).
3- Other (1%):
- Electrolytes.
- Hormones.
2- Proteins (7%):
- Albumin (the most abundant plasma
protein, responsible for maintaining
blood osmotic pressure).
- Globulins (transport factors).
- Fibrinogen (clotting).
- Complement proteins (important
defensive system).

9. What is the difference between ?
Plasma Serum

10. 2- Red
blood cells
- They are also called erythrocytes, are
terminally differentiated cells, flexible
biconcave in shape, lacking nuclei and
filled with O2 carrying protein called
hemoglobin.
- There life span is about 120 days.

11. Note that:
- RBCs plasmalemma consists of 50% protein,
40% lipid and 10% carbohydrates.
- RBCs depend mainly on anaerobic glycolysis
because they lack mitochondria.
- They loss there nucleus shortly before
release by bone marrow so they can’t
replace defective proteins.

12. - RBCs carry glycosylated domains on the
external surface of there membrane called
antigens that form the basis of ABO blood
typing system.

13. FIGURE 2: Colorized SEM micrograph of normal erythrocytes.

14. MEDICAL APPLICATION
Anemia is the condition of having a
concentration of erythrocytes below
the normal range.
An increased concentration of
erythrocytes in blood is called
erythrocytosis (polycythemia).

16. 3- Buffy
coat
1- Leukocytes (WBCs).
2- Platelets.

17. Luekocytes (white blood cells or WBCs)

18. Leukocytes
Granulocytes A granulocytes

19. FIGURE 3: Leukocytes structural features.

20. 1-Granulocytes
- They contain two major types of cytoplasmic
granules: lysosomes (azurophilic granules) and
specific granules.
- They are:
1 Neutrophils.
2 Eosinophils.
3 Basophils.

21. Neutrophils
- Granulocytes with nuclei having two to
five lobes linked thin nuclear
extensions.
- They constitute 50-70% of circulating
leukocytes.
- There life span is 1-4 days.

22. - Neutrophils play an important role in
inflammatory process (first cells to
arrive) by releasing chemokines,
cytokines and important lipid
mediators.

23. FIGURE 4: Blood smears showing neutrophils. FIGURE 5: Drumstick appendage in females.

24. FIGURE 6: TEM of a sectioned human neutrophil.
N: Lobulated
nucleus.
A:
Azurophilic
granules..
S:
Specific
granules.
G:
Golgi
apparatus.

25. MEDICAL APPLICATION
Pus: Viscous, usually yellow
collection of fluid formed
during the inflammatory
process due to neutrophilic
secretions contains:
apoptotic, it neutrophils,
bacteria, semidigested
material and tissue-fluid.

26. Eosinophils
- Eosinophils are far less numerous
than neutrophils, constituting only
1%-4% of leukocytes.
- They have characteristic bilobed
nucleus.
- They act to kill parasitic worms or
helminths.

27. - They contain major basic proteins
(MBP), an arginine-rich factor that
accounts for the granule’s
acidophilia and constitutes up to 50%
of the total granule protein.
- Eosinophils life span is about 1-2
weeks.

28. FIGURE 7: Eosinophils. FIGURE 8: TEM sectioned eosinophil.

29. Basophils
- Basophils make up less than 1% of circulating leukocytes.
- The nucleus is divided into two irregular lobes, but the
large specific granules overlying the nucleus usually
obscure its shape.
- The strong basophilia of the granules is due to the
presence of heparin and it also contain much histamine
and various other mediators of inflammation, including
platelet activating factor, eosinophil chemotactic factor,
and the enzyme phospholipase A.

30. - basophils and mast cells have surface
receptors for immunoglobulin E (IgE) and
responsible for hypersensitivity type 1.
- Basophils life span is about several
months.

31. FIGURE 9: Basophils.. FIGURE 10: TEM sectioned Basophils.

32. MEDICAL APPLICATION
In some individuals a second exposure to
allergen, produce systemic response.
Basophils and mast cells degranulate,
producing vasodilation, sudden drop in
blood pressure a potentially lethal
condition called anaphylactic shock.

34. 2- A granulocytes
- They lack specific granules, but they do contain azurophilic
granules.
- The nucleus is spherical or indented but not lobulated.
- They are:
1 Lymphocytes.
2 Monocytes.

35. Lymphocytes
- By far the most numerous type of agranulocyte
and typically the smallest leukocytes.
- Spherical nuclei.
- mature lymphocytes can be subdivided according
to surface molecules called “cluster of
differentiation” or CD markers in to:
1- B lymphocytes (CD4+).
2- Helper and cytotoxic T lymphocytes (CD8+).

36. - Lymphocytes life span is about hours
to many years.
Note: T lymphocytes differentiate in
the thymus unlike other leukocytes.

37. FIGURE 11: Lymphocytes. FIGURE 12: TEM sectioned lymphocets.

38. MEDICAL APPLICATION
Lymphomas are a group of disorders
involving neoplastic proliferation of
lymphocytes or the failure of these cells
to undergo apoptosis. Although often
slow-growing, all lymphomas are
considered malignant because they can
very easily become widely spread
throughout the body.

39. Monocytes
- Monocytes are precursor cells of
macrophages, osteoclasts, microglia, and other
cells of the mononuclear phagocyte system.
- There nucleus is large and usually C-shaped.
- Monocytes life span vary from hours to
years.

40. What is the name of macrophages in skin ?
In liver ?
Langerhans cells
Kupffer cells

41. FIGURE 13: Monocytes. FIGURE 14: TEM sectioned monocyte.

42. Platelets (thrombocytes)

43. - Platelets are small non-nucleated, membrane-bound
cell fragments.
- originate by separation from the ends of cytoplasmic
processes from giant bone marrow cells called
megakaryocytes.
- They consists of lightly stained peripheral zone, the
hyalomere, and a darker-staining central zone rich in
granules, called the granulomere.
- The role of platelets in controlling blood loss.

44. FIGURE 15: Aggrigated platelets. FIGURE 16: TEM sectioned platelet.

45. Platelets aggrigation

46. MEDICAL APPLICATION
Aspirin and other nonsteroidal
anti-inflammatory agents have an
inhibitory effect on platelet they
prevent the aggregation. The
term Bleeding disorders is used
when there is abnormal slow
blood clotting.

47. Quiz
1. Which biochemical component of the erythrocyte
cell surface is primarily responsible for determining
blood type (the A-B-O system)?
a. Fatty acid
b. Carbohydrate
c. Nucleic acid
d. Protein
e. Cholesterol

48. 2. What cell in circulating blood is the
precursor to macrophages and most
antigen-presenting cells?
a. Eosinophil
b. Basophil
c. Lymphocyte
d. Monocyte
e. Mast cell

49. 3. What is the approximate life span of a
circulating erythrocyte?
a. 8 days
b. 20 days
c. 5 weeks
d. 4 months
e. 1 year

50. 4. Which cell type has cytoplasmic
granules that contain heparin and
histamine?
a. Eosinophils
b. Basophils
c. Lymphocytes
d. Monocytes
e. Neutrophils

51. 5. Which of the following blood cells
differentiate outside of the bone
marrow?
a. Neutrophils
b. Basophils
c. Eosinophils
d. T lymphocytes
e. Megakaryocytes

52. Identify the cells
RBCs and neutrophil.

53. RBCs and basophils.

54. Monocyte.

56. - Blood is a specialized connective tissue.
- Blood contain plasma and cells.
- Blood cells are RBCs, WBCs and platelets
(45%).
- The plasma form 55% of the whole blood
and its mainly water..

57. References
- Anthony L. Mescher, 2016, JUNQUEIRA’S, Fourteenth
edition, Chapter 12.
- Mischigan university website
(www.histology.medicine.umich.edu).
- The University of Western Australia website
(www.lab.anhb.uwa.edu.au).