Blood Histolgy

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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).

15. 3- Buffy coat 1- Leukocytes (WBCs). 2- Platelets.

16. Luekocytes (white blood cells or WBCs)

17. Leukocytes Granulocytes A granulocytes

18. FIGURE 3: Leukocytes structural features .

19. 1-Granulocytes - They contain two major types of cytoplasmic granules: lysosomes ( azurophilic granules) and specific granules . They are: 1\ Neutrophils. 2\ Eosinophils. 3\ Basophils.

20. 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.

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

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

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

24. 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.

25. 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 .

26. 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 .

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

28. 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 .

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

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

31. 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.

32. 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.

33. 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 + ).

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

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

36. 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.

37. 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 fr om hours to years .

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

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

40. Platelets (thrombocytes)

41. - 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 .

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

43. Platelets aggrigation

44. 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.

45. 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

46. 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

47. 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

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

49. 5 . Which of the following blood cells differentiate outside of the bone marrow? a. Neutrophils b. Basophils c. Eosinophils d. T lymphocytes e. Megakaryocytes

50. Identify the cells RBCs and neutrophil.

51. RBCs and basophils.

52. Monocyte.

53. 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. .

54. 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 ).