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histology > Platelets & WBCs > Flashcards

Platelets & WBCs Flashcards

1
Q

about Blood Platelets (Thrombocytes)
1. Number:………..
2. Increase in number………………
3. Decrease in number………….
4.Life span…………
5. Senescent platelets are phagocytosed by ………. primarily in the ………..

A
  1. 150.000- 400.000/mm³
  2. Thrombocytosis
  3. Thrombocytopenia
  4. 10 days
  5. macrophages/ spleen
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2
Q

illustrate Origin of Blood Platelets (Thrombocytes)

A

The platelets are cell fragments derived
from the megakaryocytes in the bone
marrow

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3
Q

illustrate Morphology (structure) of platelet by L.M

A
  • Size: 2 - 4 µm in diameter.
  • Shape: oval disk shaped (cell fragments).
  • Nucleus: They lack nuclei
  • they display a peripheral clear region called hyalomere and denser granular center called the granulomere
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4
Q

illustrate Morphology (structure) of platelet by E.M.

A
  • The cell membrane coated by glycocalyx (glycoproteins and glycolipids) to be involved in platelets adhesion
  • Cytoplasm: divided into 2 regions:
    1. Hyalomere:Peripheral clear region
    2.Granulomere:Central granular region
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5
Q

illustrate Hyalomere

A
  • It is the peripheral part. It shows:

a) Marginal bundle consisting of:
- 10 -15 microtubules arranged parallel to each other forming a ring within the hyalomere. They assist in maintaining the discoid form of the platelets.
- Actin and myosin microfilaments helping contraction of the platelets during retraction of blood clot.

b) Two tubular systems:
- Open canalicular system: which is invagination from the cell membrane, facilitating platelets’ uptake of factors from plasma. Also, this system facilitates rapid degranulation upon activation and Ca release.
- Dense tubular system: which may be remnants of endoplasmic reticulum of megakaryocytes (stores Ca ions)

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6
Q

illustrate Granulomere composition

A
  1. Mitochondria
  2. Glycogen
  3. (3) types of granules :
    Delta, Alpha, lambda
    - Alpha granules (majorty):
    Fibrinogen
    PDGF
    coagulation factors.
    Platelet factor 4.
    - Delta granules:
    ADP
    ATP
    Ca
    Serotonin
    - Lambda granules:
    Lysosomes
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7
Q

illustrate Development of platelets
(thrombopoiesis)

A
  • Platelets are continuously produced in red bone marrow.

1- Stem cells:
- Pluripotent hemopoietic stem cell (PHSCs)
- multipotential myeloid stem cell

2- Progenitor cells:
- colony forming unit megakaryocyte (CFUMeg)

  1. Megakaryoblast (Immature
    megakaryocyte):
    - Size: large cell 25-50μm.
    - Nucleus: large with numerous nucleoli.
    - Cytoplasm: highly basophilic homogenous non-granular.
    - Before differentiation, they undergo endomitosis, with repeated rounds of
    DNA replication not separated by cell divisions, resulting in a nucleus that is
    highly polyploid

4.Megakaryocyte (mature cell) :
- Size: a giant cell up to 150 μm
- Nucleus: large lobulated and polyploid.
-Cytoplasm: basophilic - granular.
-It contains numerous mitochondria,well
developed rER, extensive Golgi complex, α granules, lysosomes (lambda granules) and dense bodies.Megakaryocytes are located near sinusoids, extend their long
processes through fenestrae of endothelial cells into the sinusoidal lumen. Platelets are separated from the top of these processes and washed out with circulation.Invagination from cell membrane forming the demarcation membranes that represent reservoirs for rapid elongation of the processes.

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8
Q

about Megakaryocyte
1. Is a ………….cell
2. Nucleus is large ….. stained.
3. Cytoplasm is …………

A
  1. giant
  2. lobulated & deeply
  3. basophilic.
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9
Q

list def & classification of Leucopoiesis

A
  • it is the development and maturation of WBCs.
  • It is classified into two main categories of Development of :
    1- granulocytes.
    2- agranulocytes
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10
Q

illustrate GRANULOPOIESIS

A
  • PHSCs→ multipotent myeloid stem cells→ colony forming unit- granulocytes-monocytes (CFU-GM) → Myeloblasts.
  1. Myeloblasts:
    *large and rounded cells with basophilic, non-granular cytoplasm.
    *Large, rounded nucleus with one or more nucleoli.
  2. Promyelocytes:
    *Larger in diameter with large nuclei.
    *Basophilic cytoplasm that contains non-specific azurophilic granules
  3. Myelocytes:
    * Smaller in size.
    * The nucleus has a deep indentation and assumes an eccentric position within the cell.
    * The cytoplasm is basophilic, contains both types of granules; specific and non-specific. So, there will be three types of myelocytes:
    ❖ Neutrophilic myelocytes: with specific neutrophilic granules.
    ❖ Eosinophilic myelocytes: with specific acidophilic granules.
    ❖ Basophilic myelocytes: with specific basophilic granules.
    At this stage, myelocytes lose their capacity for mitosis and they change to metamyelocytes (stop mitosis).
  4. Metamyelocytes:
    * Smaller cells with more specific granules
    * and less developed organelles.
    * Nucleus becomes kidney-shaped with more condensed chromatin.
    * Neutrophilic metamyelocytes pass through an intermediate stage where the nucleus becomes curved rod (band cells), then, they pass to mature neutrophils with segmented nucleus.
  5. Mature granular leucocytes.
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11
Q

illustrate Lymphopoiesis

A
  1. PHSCs→CFU-Ly→CFU-T lymphocytes→ T lymphoblast
    (large cells), that migrate to the thymus cortex → Prolymphocytes (smaller, acquiring their specific cell surface
    markers according to the environment) → T-lymphocytes.
  2. PHSCs→CFU-Ly→CFU-B lymphocytes→ B lymphoblast (large cells) → Prolymphocytes (smaller, acquiring their specific cell surface markers according to the environment) → B- lymphocytes and NK cells in bone marrow.
  3. Mature B and T lymphocytes leave the bone marrow and thymus respectively and circulate to reach peripheral organs as lymph node and spleen
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12
Q

illustrate Monocyte Development

A
  1. Occurs in red bone marrow
  2. Stem cells:
    - PHSCs
    - multipotential myeloid stem cells
  3. Progenitor cells:
    - colony forming unit- GM
    - CFU-monocytes
  4. Precursor cells:
    - Monoblast
    - Nucleus: Large pale staining with prominent nucleolus.
    - Cytoplasm: Basophilic
    - Pro-monocyte
    - Nucleus: large intended with numerous nucleoli.
    - Cytoplasm: basophilic.
  5. Mature cells:
    - Monocyte
    - Mature monocytes circulate for only 8 hours
    - They enter CT and differentiate into macrophages which function for several months.
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13
Q

about Leucocytes (White blood cells)
1. Are true……….., having nuclei and organelles.
2. Are ………….. than RBCs.
3. Have ………… life span.
4. Normally, total leucocytic count is about………….

A
  1. spherical cells
  2. larger and much less numerous
  3. shorter / (most last hours to days).
  4. 4.000-11.000/mm³.
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14
Q
  • Classify leucocytes
A
  1. Granular :
    - Neutrophils
    - Eosinophils
    - Basophils
  2. Non-granular :
    -Lymphocytes
    - Monocytes
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15
Q

about Neutrophils (Polymorphonuclear
leukocytes)

  1. Number………….. of total leucocytic count.
    - by L.M.
  2. Size : ………….
  3. Shape: …………..
  4. Nucleus: …………….
  5. Cytoplasm: ……………..
  6. Life span: ……….in blood and ………… in connective tissue before dying by ………………
  7. Some mature neutrophils of human female show ……….. as a drum stick appendage (Barr body), which is the inactive X-chromosome.
  8. while the immature cells (band neutrophils) contain ………………… nucleus. Band neutrophils are not more than ……….in blood film under normal condition
A
  1. 60-75%
  2. 12-15 µm
  3. Rounded
  4. condensed and segmented
    (multilobed, formed of 3- 5 lobes
    connected by thin strands of chromatin).
  5. is heavily populated with fine neutrophilic granules.
  6. 6-8 hours / 1-4 days / apoptosis.
  7. sex chromosome
  8. one bent rod (or horse-shoe) / 1-2%
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16
Q

about Neutrophils (Polymorphonuclear
leukocytes) By E.M.

  1. Few organelles………….
  2. Membrane-bounded granules
    I…………….
    II…………….
A
  1. (mitochondria, small Golgi complex and rER)

2.
I. 1- Neutrophilic granules 80%
II. - Azurophilic granules (20%):
lysosomes

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17
Q

list chc of Neutrophilic granules

A

-small & numerous
- Alkaline phosphatase
- Bacteriostatic enz (lactoferrin).
- Collagenase

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18
Q

list chc of Azurophilic granules

A
  • Large& few
  • Hydrolytic enzymes
  • Proteolytic and lipolytic
19
Q

list function of Neutrophils (Polymorphonuclear leukocytes)

A
  • body defense (in pyogenic infection):
    Neutrophils are the first line of defense against bacterial invasion
  • Apoptotic neutrophils, bacteria, semi-digested material, and tissue fluid form a viscous, usually yellow collection of fluid called pus
20
Q

about Eosinophils
1. Number ….. of total leucocytic count.
2. Life span……… in blood and …….. in connective tissue.
3. Increased number ………………
(in ……………..)

A
  1. 1-5%
  2. Few hours / 1-2 weeks
  3. Eosinophilia / allergy & parasitic infestation
21
Q

about eosinophil by L.M.
1. Size & shape: ……….
2. Nucleus: …………..
3. Cytoplasm: ………….

A
  1. rounded cells, 12-15 µm in diameter.
  2. bilobed or horse-shoe
  3. small Golgi apparatus, few mitochondria, rER, moderate
    amount of glycogen. packed with numerous large, refractile and acidophilic granules
22
Q

illustrate Membrane-bounded granules in eosinophil

A
  1. Specific granules :
    - large ovoid
    - Crystalline electron dense core = internum surrounded by less dense zone called the externum.
  2. Azurophilic granules:
    - Lysosomes
23
Q

illustrate content of Membrane bounded specific granules

A

1- major basic proteins (MBP) and eosinophilic peroxidase (both
have anti-parasitic worms & helminths).
2- contain histaminases and arylsulphatase (anti-allergic) which
degrade histamine and slow reacting substance of anaphylaxis (SRSA) released by mast cells and basophils during hypersensitivity reaction

24
Q

what about Azurophilic granules ?

A

smaller and less in number.
They are lysosomes containing hydrolytic enzymes (anti-parasitic and also hydrolyze the Ag-Ab complex)

25
Q

about Basophils
1. Number………… of total leucocytic count.
2. Life span………. in blood and …………… in connective tissue.
3. Increased number ………….in………

A
  1. 0.5-1%
  2. Few hours / several months
  3. basophilia / allergic reactions
26
Q

describe basophil by L.M. & E.M.

A

L.M.:
1. Size & shape: rounded cells, 10-12 µm in diameter.
2. Nucleus: is irregular (or S-shape).
3. Cytoplasm: is packed with large basophilic granules masking the nucleus
(metachromatically stained by Toluidine blue)

E.M.:
1. Few organelles.
2. Membrane-bounded granules
- Specific gr. :
Large electron dense.
Contain heparin, histamine, ECF & NCF.
- Azurophilic granules :
Few lysosomes

27
Q

illustrate the function of basophil

A

Function:
1. Release of specific granules content promotes allergic reaction similar to mast cells.
2. Histamine causes vasodilatation and smooth muscle contraction

28
Q

about Lymphocytes
1. Constitute ……..
of total leucocytic count.
2. Life span…………… vary according to their specific functions; some live only a…….. and others survive in the circulating blood or other tissues for

A
  1. 20-25 %
  2. few hours / many years
29
Q
  1. Lymphocytes are classified according to ……………
  2. into :
    - …………..
    -…………….
    -……………..
A
  1. their size
    2.
    - Small Lymphocytes
    - Medium sized lymphocytes
    - Large sized lymphocytes
30
Q

about Large lymphocytes:
1. ……….. in diameter.
2. They are present mainly in …..
3. The majority of large lymphocytes seen in blood represent ………
4. Some circulating large lymphocytes are …………

A
  1. 15-18 μm
  2. lymphatic tissue.
  3. activated B lymphocytes
  4. natural killer (NK) cells
31
Q

Both medium & large lymphocytes are …………..

A

activated lymphocytes

32
Q

classification of lymphocytes according to function :
1. …………
2. ………….

A
  1. T Lymphocytes
    Mature in Thymus
  2. B Lymphocytes
    Mature in BM
33
Q

describe shape of lymphocytes

A

Shape: Both B & T lymphocytes are similar in appearance. The small cells are spherical with large central, rounded and condensed nucleus

34
Q

describe Nucleus of lymphocytes

A

Small lymphocytes have spherical nuclei occupying most
of the cell while the Larger lymphocytes have larger, slightly
indented nuclei.

35
Q

describe shape of lymphocytes By E.M

A
  • Few organells but many free ribosomes.
  • Few azurophilic granules (lysosomes).
  • Surface is covered by microvilli.
36
Q

describe Cytoplasm of lymphocytes

A

Small lymphocyte show thin rim of basophilic cytoplasm surrounding the nucleus, while larger lymphocytes
show more slightly basophilic cytoplasm

36
Q

describe Cytoplasm of lymphocytes

A

Small lymphocyte show thin rim of basophilic cytoplasm surrounding the nucleus, while larger lymphocytes
show more slightly basophilic cytoplasm

37
Q

about small lymphocytes
1. percentage……..
2.size ……
3. nucleus………
4. cytoplasm……..
5. EM………

A
  1. 92% of circulating lymphocytes
  2. 6 – 9 μm
  3. Rounded indented
  4. Thin rim of basophilic cytoplasm
    surrounding the nucleus
  5. Many Free ribosomes Few Mitochondria, Golgi complex and rER
38
Q

about medium lymphocytes
1. percentage……..
2.size ……
3. nucleus………
4. cytoplasm……..
5. EM………

A
  1. 8%
  2. 10 – 15 μm
  3. Larger indented, lightly stained
  4. More cytoplasm, slightly basophilic
  5. Large number of mitochondria, abundant rER, few polysomes, well-developed Golgi complex.
39
Q
  • To differentiate between B and T lymphocytes, ………..are used to specific surface markers
A

labeled antibodies

40
Q

about Monocytes
1. Number ….. of total leucocytic count.
2. Size & shape ……….
3. Nucleus………..
4. Cytoplasm……….
5. Organelles………..
6. Life span ………….

A
  1. 3-8 %
  2. rounded large cells, 12-20 µm.
  3. large, kidney-shaped
  4. basophilic, many azurophilic granules
    (lysosomes).
  5. mitochondria, prominent Golgi complex, few rER, sER and ribosomes.
  6. From few hours to many years
41
Q

illustrate the function of monocytes

A
  1. They migrate to the connective tissue to differentiate into macrophages.
  2. Circulating monocytes are highly phagocytic cells. They phagocytose bacteria, virus and foreign bodies
42
Q

1…………………., extravasation of monocytes occurs, and they change into macrophages that migrate to the connective tissue at the site of injury.

  1. …………………….., continuous recruitment of monocytes occurs leading to continuous presence of macrophages causing excessive tissue damage.
A
  1. In acute inflammation
  2. In chronic inflammation

histology (7 decks)

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