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Flashcards in Hematology Deck (30):

What is extra medullary hematopoiesis and when does it occur?

hematopoiesis occuring outside of the medullary cavity.

This can occur during fetal development where hematopoiesis will occur in the liver or spleen.

This can also occur during pathological process such as myelofibrosis where fibrosis occurring in the bone marrow forces hematopoeitic cells out of the marrow into the spleen or liver.


Comment on the difference between young and old animals bone marrow...

Young: Have red, active marrow producing many RBC's (the need for new RBC's is high)

Old: Limited parts of the marrow are producing cells. Active marrow is usually at the end of the long bones. They contain yellow marrow in the region of the diaphysis which consists of fat and supporting cells. This area does have the ability for active marrow to infiltrate.


What is the first recognizable cell seen in erythropoiesis?



What is the first cell seen in bone marrow aspirates? What is a unique feature of this cell.

Erythroblast. Round Nucleus. Very blue.


What is a unique characteristic of Normoblasts?

They have a condensed, shiny black nucleus poking out of the side of the cell and eventually it will get rid of the nucleus.


What are reticulocytes?

They are immature, anucleated, red blood cells that develop and mature in the red bone marrow. They circulate for about a day or two before maturing into an RBC.


Splenic Sequestration

This occurs in dogs and horses. During times of stress or nervousness will get a splenic contraction (spleen is a reservoir for RBC's) which will cause an increase in circulating RBC's however this is a transient situation. Circulation numbers will return to normal. Keep this in mind when sampling to not confuse with blood disorder.


Describe the progression of Granulopoiesis.

1. Multipotential stem cell
2. Unipotential stem cell
3. Myeloblast (first recognizable cell)
4. Promyeloctye
5. Myelocyte
6. Metamyelocyte
7. Band Neutrophils
8. Mature Neutrophils/ segmenters ( wait in the bone marrow for stimulus to allow release)


A higher than normal number of circulating reticulocytes could indicate what?

1. Bleeding
2. Hemolytic Anemia
3. Increase production of EPO in the kidneys


What stain can be used to test for increased/ decreased reticulocytes in the blood sample?

When immature red blood cells are stained with a supravital dye, the cytoplasmic RNA is precipitated into a reticulum-like network.


Describe the lifecycle of an erythrocyte beginning in the bone marrow.

1. Matures in the bone marrow from a multi potential stem cell to a reticulocyte over a 5 day period.

2. The reticulocyte is released into circulation and circulates for ~48 hours until it matures into a RBC.

3. Depending on the species, the RBC will circulate for "x" amount of days until is aged enough to be phagocytosed my macrophages primarily in the spleen but possibly in the liver and bone marrow as well.

4. When becoming phagocytosed, the macrophages break down the RBC into bilirubin, Fe, and protein.

5. The bilirubin is then transported to the liver via the plasma protein albumin. The Liver will conjugate bilirubin into a H20 soluble product allowing it to be come excreted.

6. The Fe will be transported and recycled back into the bone marrow for further use.


What is the RBC life span of:
a. Horse
b. Cow
c. Dog.
d. Cat.
e. Mice

A. 145
B. 130
C. 120
D. 70
E. 43


What is EPO, what is its purpose, and where is it produced?

Erythopoietin is a hormone produced by the kidneys in response to HYPOXIA. It will enter the circulation, travel to the marrow, and stimulates the proliferation of erythroid progenitors (undifferentiated stem cells in the bone marrow)


Describe the life cycle of a neutrophil beginning the bone marrow..

Multi potential stem cells mature in Neutrophils after ~6 days in the bone marrow. Neutrophils enter the circulation for ~ 7-14 days and then can either be
- Circulating neutrophils where the stay in the
in the central axis of the blood stream. OR
- Marginating neutrophils that creep along the walls of the endothelium waiting to move into tissues in response to inflammation/ infection.

When taking a blood sample you will sample the circulating neutrophils.

Once neutrophils have entered the tissues they will not re enter back into circulation. They will either be lost from the body or phagocytosed by macrophages.


Describe the life span of eosinophils...

Eosinophils take 2-6 days to mature in the bone marrow. They will enter the circulation and circulate for 1-24 hours before entering tissues (skin, GI, resp). They will last in the tissues for as shorts as 2 days and as long as 2 weeks.


Describe the life span of a monocyte...

Monocytes have short transit time in the blood. When they are recruited into tissues they differentiate into macrophages.



Lymphocytes are recirculating. Lymphopoiesis occurs in the Bone marrow (B-cells), Thymus (T-cells) and in birds occurs in the Bursa of Fabricius.


What species has the largest RBC size in regards to cats, dogs, horses, cows.

Dogs > horses> cats> cows


What is unique about RBC circulation in horses?

You will not see immature red blood cells circulating. NO RETICULOCYTES!!


What is rouleaux formation and what species would you not be concerned if you saw this?

RBCs have a negative charge. If there is an increase in the bloods viscosity the blood is overwhelmed and RBCs stack like coins. "Rouleaux formation"

It is normal for horses to have rouleaux formation. If this is seen in cats there is some inflammatory response occurring.


Comment on RBC circulation in regards to young animals, sight hounds, and warm v. cold blooded horses.

Young animals have a lower circulation of RBCs (do not mistake for anemia)

Sight hounds have a physiologic increase in circulation RBCs

Warm v. Cold blood horses show seasonality in circulating RBCs


Comment on morphology of Canine RBC's

The canine erythrocyte in health is a relatively large, uniform, biconcave disc. Have a really good area of central pallor


Comment on morphology of Feline RBC's

Cat erythrocytes are smaller and more variable in size and shape than those of dogs and lack the central pallor that dogs contain.


Comment on morphology of Cow RBC's

Lack a good area of central pallor similar to cats.


Comment on morphology of Horse RBC's

Rouleaux formation is normal. No immature RBCs in circulation.

Raspberry like eosinophils


Comment on morphology of Alpaca RBC's

Elliptical RBCs


What is unique about the RBC life span in rabbits, rats, mice?

You will see increase #'s of reticulocytes in circulation in normal patients because mature RBCs have a decrease lifespan, therefore they have increased turnover, and therefore increased reticulocytes.


Comment on morphology of Lizard/ Fish RBC's

They have nucleated RBCs.


What are reference intervals and what must we take into account when looking at them?

Reference intervals describe the range of results expected for a healthy population of animals using the central 95% of population.

Reference intervals are specific for the instrument or machine/ analyzer used therefore must not compare results from one analyzer with another.

These reference intervals are not always representative because some animals that are perfectly normal have physiologic differences (age, breeds) in there CBCs and chemistry's that these machines do not account for.


Why is it important to make a blood smear?

1. Verify's the analyzers figures.

2. Identifies artefacts (platelet clumps, cell lysis)

3. Identifies morphological changes, abnormal cells, parasites.

Ideally, should make blood smear at the time of sampling because the sample is fresh, whereas if let the blood sit in the tube can cause degeneration sometimes.