* Parasite destruction (via catonic proteins, peroxidase & oxygen metabolites)

*Down regulation of inflammation & allergic reactions (via neutralising histamine)

* Phagocytosis of anigen-antibody complexes

How long do eosinophils spend in the circulation?

Where do they travel next and how long do they spend there?

In circulation 1-4hrs.

Then into tissues where they can survive for about 12 days.

Nucleus - less dense & not as segmented as neutrophil.

Granules - may completely fill cytoplasm.

-Highly eosinophillic (pink-orange)

Cytoplasm - If visible appears light blue.

The content of Basophil granules varies between species.

List 5 things they can contain.

1. Heparin

2. Hydrolytic enzymes

3. Histamine

4. Seratonin

5. Other vasoactive substances

1. IgE (bound to specific antigen) - Most commonly

2. Physical stimuli

3. Chemical stimuli

Mast cells.

Mast cells are larger and have a round nucleus.

It is thought possible that mast cells & Basophils arise from a single early precursor cell.

1.Producing an immediate allergic reaction.

2.Limited phagocytic & bactericidal capabilities.

 3. Substances released from basophils can induce smooth muscle contraction & increase vascular permeability.

"Base loving"

Purple in romanowsky stains.

"Azure loving"

Purple in romanowsky stains

"Acid loving"

Eosinophillic in Romanowsky stains

= orange

1. Monocytes

2. Lymphocytes

Monomorphonuclear leucocytes have a single, roundish nucleus.

1. Neutrophils

2. Eosinophils

3. Basophils

Granulocytes have a single nucleus that is segmented or lobed and granules (lysosomes) in their cytoplasm.

Describe a typical mature mammalian erythrocyte.

Why are they like this?

 - Biconcave disks

Maximal possible surface area : Vol ratio.

Minimal tension on membrane when shape changes.

 - Pink/orange stainingwith central pallor

The haemaglobin inside the cell gives it this colour (central pallor due to biconcave shape)

 - No Nucleus/organelles

Without organelles the cell can carry the maximum possible volume of haemaglobin.

Refers to when mammalian erythrocytes adhere to each other & form chains.

Can be an indication of inflammation

but is often seen in normal horse/cat/dog blood.

Glucose metabolism

-95% derived from anerobic glycolysis

-5% via oxidative pentose phosphate pathway.

What is spectrin?

What is its function?

It is a cytoskeletal protein.

It forms a network beneath the plasma membrane of an erythrocyte, which maintains and stabilises the cell's shape.

Erythrocytes need to squeeze throughsmall capillaries so need to be very deformable.

Where are erythrocytes produced?

How long do they survive in the circulation?

Produced in the bone marrow.

Life span varies with species but ranges from 60-160 days.

Pig - 60

Cat - 70

Dog - 110

Horse - 150

Ox - 160

Sheep 70-150

What is the typical size of a mammalian erythrocyte?

How does this vary between species?

size = 4-10micrometres

Cat - 5.6

Rabbit - 6.6

Dog - 7.2

Human - 7.8

Elephant - 9.1

Generally the larger the cells are, the less there are.

Most species have same erythrocyte mass/L of blood.

Largest of the leucocytes

12-18 micrometres

-Unsegmented nucleus

- Nuclear shape varies - round, indented, folded, bean-shaped, horseshoe shape, amoeboid (irregular?)

-Nuclear chromatin appears reticular or "lacy"

- Relativley abundant blue-grey cytoplasm

- Cytoplasmic vacuoles often present

 - May have purple azurophillic granules in cytoplasm

Where are monocytes produced?

Once leaving there, where do they go?

-Produced in bone marrow

- Enter circulation

 - Rapidly leave circulation and enter tissues & body cavities. Here they turn into macrophages.

-Can remain in tissue for weeks - years.

What % of circulating leucocytes is made up by lymphocytes in...

-Dogs, cats, horses?

- Pigs & ruminants?

- Dogs, cats, horses = 20-40%

- Pigs & ruminants = 50-70%

- Round (or slightly indented) nucleus

- Intensely staining nucleus

 - Thin rim of pale blue cytoplasm

Divided into "small" and "large"  - doesn't necessarily imply functional difference.

 - Small - 6-9 micrometres.

dense nucleus, scant deep blue cytoplams

- Large - 9-15 micrometres

nucleus less dense & may be indented

More cytoplasm - paler blue

What are the three main types of Lymphocytes?

What are the sub-groups of each of these types?

 1. B Lymphocytes (B cells)

no further subdivision

 2. T Lymphocytes (T cells)

- T helper Cells (CD4+)

- T Cytotoxic (CD8+)

- Tregulatory Cells (T regs)

3. Null Lymphocytes

 - Undifferentiated (Immature)

- Natural Killer Cells (NK cells)

CD8+  = Cytotoxic T cell

-Sub-type of lymphocyte

- Effecters of cell-mediated cytotoxicity

(Cell Killing)

Supress aspects of immune responses to prevent autoimmune damage.

Regulation is mediated by cytokines.

CD4+ = Helper T cell

Subtype of lymphocyte

-Once expose to a processed antigen they regulate the immune responses.

- Regulation is mediated by the secretion of cytokines.

- Cytokines affect the activity of B cells and cytotoxic T cells

What is the difference between a null cell and B/T cells?

-B and T cells have specific surface molecules known as CD antigens (CD4+, CD8+)

- Null cells lack the surface molecules

NK Cells have a role in cell mediated cytotoxicity.

(eg. against tumor cells)

- Irregular segmented/lobed nucleus (up to 5 segments)

- The older the cell, the more segments

-Pale blue-grey cytoplasm

-May have pale-purple granules in cytoplasm

- Barr body may be present (females only)

Where are neutrophils produced?

How long is their lifespan?

Where do they spend their time?

-Produced in the bone marrow

 - Total lifespan = approx 8 days

*Mostly in bone marrow

* 10hrs in circulation

* 2-3 days in tissue

First line of defence against bacterial infections

- Pahgocytic (eat bad cells)

- Prominent in early phase of inflammation

- Rapidly migrate to infection site, adhere to blood vesselwall, then move through it to affected site.

- Migration is in response to complement (serum proteins) and chemotaxins.

-A leucocyte unique to reptiles.

-A type of mononuclear cell

 - The nucleus is usually round

- Pink-purple cytoplasm

-Thought to be a monocyte with distincive staining pattern.

-Present in high numbers in snakes but low in crocodiles, lizards and turtles.

What is a Heterophil?

Heterophils are the avian & reptile equivalent of neutrophils.

-Cytoplasm is colourless or pale pink & contains granules.

- Birds - nucelus is bi-llobed.

 - Reptiles - nucleus usually unlobed and round or oval.

- No nucleus

- have organelles and granules

 - Variable in shape - round/elongated

 - Very small

 - Hyalomere - outer clear zone.

 - Granulomere - Inner zone with azurophilic granules

- Cytoplasm also contains glycogen, ribosomes & canaliculi (these open at the surface)

What is the lifespan of a platelet?

Where do they spend their time?

Lifespan - 5-10 days

-circulation

-There are large reserves of platelets in the spleen

 - Aged platelets are removed by macropahges in spleen, liver & bone marrow

- Maintenance of heamostasis & vascular intetgrity

 - Plug defects in vessel walls by adhering to each other & to the site.

 - Produce substances to accelerate coagulation & activate/ aggregate other platelets.

 - release vasoconstricors & accelerate clot retraction.

 - Play a role in phagocytosis & inflammation

 -

-Parrot eosinophils have pale blue staining granules.

- Snakes may have dark blue granules.

 - Nucleus usually lobulated in birds & unlobulated in reptiles.

 - Avian/reptile quivalent to platlet.

 - Entire, nucleated cells.

 - Round/oval with clear or very pale grey/blue cytoplasm.

-Nucleus is round or oval and fairly dense.

-Cytoplasm may contiain a few azurophilic granules.

 - Activation indicated by aggregation, altered cell shaped & vacuolation of cytoplasm.

1. Erythropoietin (erythrocytes)

2. Thrombopoietin (platelets)

3. Colony Stimulating Factors

-A Cytokine

- GM-CSF (granulocyte-macrophage)

4. Interleukins

-A cytokine.

-Mostly influences lymphocyte production.

Whav happens to a developing erthrocyte as it matures?

-Cell size decreases

-Cytoplasmic RNA is replaced by haemaglobin

(Colour changes from blue to pink/orange)

-Nucleus becomes smaller, loses its nucleoli and is eventually lost.

What is the first morphologically recognisable Erythroid cell called?

Describe it.

It is a Rubriblast.

(also called pronormoblast or proerythroblast)

Very large and has deep blue cytoplasm & a round nucleus with 1-3 nucleoli.