Dr. AmalM. Moustafa, Department of Histology & Cytology · 2011-06-19 · Dr. AmalM. Moustafa, Department of Histology & Cytology C-Colour:-• Fresh, single RBC is greenish yellow

Dr. Dr. AmalAmal M. M. MoustafaMoustafa, Department of Histology & Cytology, Department of Histology & Cytology



The BloodThe Blood


The BloodThe Blood• Definition:-• It is the viscid fluid, present in the closed

circulatory system.• Contents:1-blood cells:• They form about 45% of the blood volume.• The Blood cells are:-

– a- Red cells (erythrocytes).– b- White cells (leukocytes).– c- Blood platelets (thrombocytes).

2-Plasma: it forms 55% of the blood volume.


The Blood CellsThe Blood Cells


RED BLOOD CORPUSCLES (RBCS)Erythrocytes

• A- Shape of RBCs:-• They are rounded, biconcave

disc shape. • In slow blood stream and in blood

film they adhere together forming “Rouleaux” due to high surface tension.

• B- Size:-• Normal diameter:• 6-9 um • (average 7.5 um).


C- Colour:-• Fresh, single RBC is greenish

yellow due to minimal HB.• A drop of blood appears red as

it contains large number of RBCs.

• In stained sections, RBCs with normal HB appear acidophilic with pale centre (normochromic).

• D- Number:-• In males: 5 - 5.5 million /mm3. • In females: 4.5 - 5 million

/mm3.(due to loss of blood during menstruation and depression of bone marrow by female sex hormones).


E- Structure of RBCs:-• They are non nucleated cells (now called corpuscles).• They have no organoids but filled with HB.• They are surrounded by cell membrane, which is plastic and has selective

permeability.• They contain important enzymes e.g. carbonic anhydrase enzyme.• Adaptation of RBCs to its function:-• Its biconcave shape increases surface area for more gas

exchange. • Absence of nuclei and cell organoids allows more space to HB

for gas exchange. • Carbonic anhydrase enzyme plays an important role in

transportation of CO2 from tissues to the lung.• Selective permeability of the cell membrane allows easy

exchange of oxygen and CO2 but not HB.• Plastic cell membrane allows RBCs to be squeezed in narrow

vessels, then regain its normal shape in wide vessels thus prevent their rupture.


LEUCOCYTES (WBCS)• - :Definition• They are true nucleated cells having cell

organoids, cell inclusions, but no hemoglobin.• :Colour• Single WBC is colourless (leucocyte) but when

aggregated, they appear white (WBCs).• :Number. 4000-11000/mm3


Classification of leucocytes:

-1-Granular leucocytes:- 2- Non-granular:-a- Neutrophils. a- Lymphocytes.b- Eosinophils. b- Monocytes.

• c- Basophils.


Neutrophils)polymorphonuclear leucocytes(

• Percentage: 60-75% of total leucocytes.• Shape: spherical• Size: 10-12 um.• Nucleus:-• Single, dark stained and segmented (2-5

segments connected by fine chromatin threads.• About 60% of female nuetrophils have Barr

bodies attached to their nuclei.• Cytoplasm:- contains fine neutrophilic

granules.


E/M:

• Few mitochondria and• endoplasmic reticulum.• Two types of granules are present:-• Specific granules:• Numerous & small in size.• Contain bacteriostatic and bactericidal substances. • Azurophilic granules:• Few in number & large in size.• Contain hydrolytic enzymes (lysosomes). • Life span: 1- 4 days.


-Function:

• Defense against microorganisms.• When microorganism invades the surrounding tissue,

the neutrophils migrate from the capillaries and phagocytose it (so called microphages).

• They also secrete proteolytic enzymes.• During infections, they stimulate the bone marrow to

produce more leucocytes (neutrophilia).• They attract monocytes to the infected area.• Precipitate in pus formation.• They secrete trephone substances, that help in

healing of wounds.


Eosinophils• Percentage: 2- 5% of total leucocytes.• Shape: spherical• Size: 12-15 um.• Nucleus: Bilobed “horse shoe-shaped”.• Cytoplasm: contains acidophilic refractile

granules.• E/M:• Few mitochondria, rER, and Golgi. • Coarse ellipsoid granules, with electron dense

crystalloid core in the centre. • These granules contain histaminase and

sulphatase enzyme.• Life span: 8-12 days.


-Function:1-In allergic conditions, the mast

cells attract eosinophils to the site of allergy to perform anti-allergic action through:

2-They can phagocytose the antigen-antibody complex.

3-They secrete histaminase and sulphatase enzymes which destroy histamine and sulphatesubstances of allergy.


Basophils• Percentage: ½ - ١ % of .total leucocytes • Shape: spherical• Size: -١٠- ١٢ .um• Nucleus: .Large and irregular• -:Cytoplasm• Filled with large basophilic granules.• These granules can be stained metachromatic .• They also stained with Giemsa stain.• E/M• They contain coarse electron dense granules.• These granules contain histamine and heparin.• Life span ١٠-١٥ : .days• -:Function• They produce heparin and histamine during allergy.• They have minimal phagocytic activity.• They release eosinophil chemotactic factor.


Lymphocytes•Non granular leucocytes

Percentage: 25-30%.• Classification :1-Small sized lymphocytes: 4-7 um.2-Medium sized lymphocytes: 7-10 um.3-Large sized lymphocytes: 10-15 um. • Lymphocytes found in the blood are mainly

small and medium sized, while the lymphoid organs contain the three types.


sized lymphocytes-Large or medium

• Percentage: 5-10%.• Size: ١٠ - ١٢ um .• Nucleus: Large, pale and

indented .• Cytoplasm: abundant, more

basophilic and non granular .• E / M - :• The cytoplasm contains

polyribosomes, numerous mitochondria, large Golgi and lysosomes.


Small Lymphocytes• Percentage: 15-20%.• Shape: spherical.• Size: 6-8 um.• Nucleus:-• Central, round and dark stained.• Surrounded by a thin rim of cytoplasm. • Cytoplasm:- few in amount & pale

basophilic.• E/M:-• They have few ribosomes, few

mitochondria, a very small Golgi and few azurophilic granules.

• Classification:-• B. lymphocytes.• T. lymphocytes .


lymphocytes-B• :Development• U.M.C in the bone marrow colony forming cells … B .lymphoblast … B .lymphocyte.• Percentage: 30% .lymphcytes • Types:• B.lymphocytes of humoral immunity.• B.memory cells.• :Life span .3months• Function• 1- Humoral immunity:• When exposed to antigen, they are activated into medium sized lymphocytes.• Some of the active cells are differentiated into plasma cells which produce

antibodies.• This is called primary immune response.

2- Secondary response (B memory cells):• Some of the active cells are not changed into plasma cells but remain as memory

cells.• When exposed to the same antigen again, they produce more rapid and more

extensive humoral immune response.


T. Lymphocytes• Development:• UMC in the bone marrow colony

forming cells which migrate to the thymus gland where they develop into T.lymphocytes (thymus dependent).

• :Percentage• ٧٠ % of small lymphocytes

• :Life span .years• :Types• T. killer cells: produce cytotoxic

substances.• T. memory cells• T. helper cells.• T. suppressor cells.• Lymphokines secreting cells.


T. Lymphocytes•Function:

• Cell mediated immunity:-• When exposed to cellular antigen, the T-lymphocytes are activated and

come in contact with the antigen.• They secrete cytotoxic substance to destroy it. • Graft rejection cells in organ transplantation:• )by cell mediated immunity .(• T-memory cells:• Some of the activated T-cells remain in the body as memory cells, that

can attack the same antigen after a long period of time.• T-helper cells:-• T-lymphocytes, can help the B-lymphocytes to be activated by the

antigen.• .٥ Se cretion of lymphokines:• Interferon: antiviral.• Colony stimulating factor: stimulate bone marrow cells.• Macrophage factor: antibacterial. • ٦ . They act as macrophage attracting cells .


Classification of lymphocytes

Types :

Cell mediated immunity

Humoral immunity Function :

years ٣ months Life span

٧٠ %30%Percentage :

In the thymusIn bone marrow Development:

T. lymphocytesB. lymphocytes


Monocytes• Percentage : 3-8%.• Size : ١٥ um .• Nucleus : .large, pale and kidney shaped• ytoplasmC: .abundant and appears pale blue *• .• M/E -:• Many microvilli and pinocytotic vesicles near the cell surface.• Few cell organelles, small Golgi and azurophilic granules

(lysosomes).• Life Span 3 Days• Function -:• Monocytes can penetrate through capillaries and venules to

reach the C.T. where they can be transformed into macrophages.


(THROMBOCYTES)PLATELETS


(THROMBOCYTES)PLATELETS • : Definition• They are fragments of cytoplasm covered with

membrane but have no nucleus (not true cells).• Origin : .in the red bone marrow megakaryocytes• Size : 2 - 4 .m�• Shape : .oval or rounded discs• Number: ١٥٠٫٠٠٠ - ٤٠٠٫٠٠٠ / mm3.• L / M :• Appear as oval or rounded non nucleated discs.• Their outer part appears transparent and pale blue

(called hyalomere). • Their central part contains dark stained granules

(called granulomere).


E/M:1-Cell membrane:-Irregular and covered witha thick cell coat. 2- Hyalomere:- contains Tubules & vesicles invaginatedfrom the cell membrane. Actin-like mirofilaments andmicrotubules to maintain the

ovoid shape of the platelet. 3- Granulomere: (chromomere): Contains:-Alpha granules: contain fibrinogen. Beta granules: mitochondria .Delta granules: contains serotonin, ATP, ADP and calcium. Lambda granules: lysosomes.Glycogen granules.


Life span: ١٠-٥ days .• Function - :• Stop bleeding (haemostasis) through : 1-Secretion of serotonin � vasconstriction �

decrease blood loss .2-The platelets adhere to the inner wall of the

injured blood vessels forming platelet aggregation or white thrombus.

3-Then, they secrete thromboblastin � change prothrombin into thrombin � change fibrinogen into fibrin network � attract RBCs

to form red thrombus (coagulation )which close blood vessels and stop bleeding.


ThrompocytopeniaPlateletMonocytosis:Monocytes

:LymphocytosisLymphocytes

Basophilia:Basophils

:EosinophiliaEosinopenia:Eosinophils

Neutrophilia:Neutropenia:Neutrophils

Polycythaemia Anaemia or:(oligocythemia)

RBCs

Number


• 1- Anaemia or oligocythemia• Decease in number is

caused by:-• A - Deficiency of iron،

vit.B 12 ،proteins، copper.• b- Defect in bone marrow �

aplastic anaemia .• c- Haemorrhage �

haemorrhagic anaemia .• d- Haemolysis � haemolytic

anaemia .• Causes of haemolysis

are -:• Incompatible blood

transfusion. • Acids and alkalies. • Bacterial toxins and viruses. • Snake venom.• Hypotonic solutions and fat

solvents.

• 2- PolycythaemiaHaemoconcentration):

• The actual number of RBCs does not increase but the volume of plasma is reduced.

• Occurs in cases of dehydration due to vomiting, diarrhea or polyuria.

• -b Compensatory polycythaemia :

• There is actual increase in production of RBCs from bone marrow.

• Occurs as compensatory to hypoxia as in:-

• The foetus due to intrauterine anoxia.

• High attitude in low O2.• Severe muscular exercise ��

need for O٢.• Congenital heart diseases � mixed

blood .• Chronic lung conditions � impaired

oxygenation of blood .


•:aNeutrophili• It is an increase

of neutrophilsabove 75%.

• It occurs in:–Pyogenic

infections: e.g. tonsilitis, appendicitis

–Myocardial infarction.

• Neutropenia:• It is a decrease of

neutrophils below 60%.

• It occurs in:• Influenza, measles ,

starvation, severe poisoning, chronic

infections eg .Typhoid &TB.


:

• Eosinophilia:Allergic diseases.Parasitic infections e.g. bilharziasis.

•E osinopenia :It occurs after:-Prolonged steroid therapy.

• Basophilia

Allergic diseases. Parasitic diseases. Liver cirrhosis.

• Lymphocytosis:• Whooping cough.• TB.• Syphilis.• Glandular fever

• Monocytosis:• Malaria.• Typhus.• TB.• Syphilis.• Glandular fever.



Practical CessionPractical CessionBlood


RBCsPLATELETSPLATELETS


NeutrophilsNeutrophils..






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Dr. AmalM. Moustafa, Department of Histology & Cytology · 2011-06-19 · Dr. AmalM. Moustafa, Department of Histology & Cytology C-Colour:-• Fresh, single RBC is greenish yellow