Erythrocytes aka rbc s
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Erythrocytes aka RBC’s. Laboratory Procedures. Hematopoietic System. Blood supplies cells with water, nutrients, electrolytes, and hormone. Removes waste products Mainly CO 2

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Erythrocytes aka RBC’s

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Erythrocytes aka rbc s

Erythrocytes aka RBC’s

Laboratory Procedures

Hematopoietic system

Hematopoietic System

Blood supplies cells with water, nutrients, electrolytes, and hormone.

Removes waste products

Mainly CO2

Cellular elements supply oxygen (RBC), protect against foreign organisms (WBC) and initiate coagulation (platelets).

Clotting factors

Blood composition

Blood Composition

Separates into three components:

Red Blood Cells (RBC’s)

White Blood Cells and platelets (buffy coat)


Bottom 1/3 to ½ of tube contains the heaviest of cellular material (the RBC’s).

Hematocrit pcv packed cell volume

Hematocrit=PCV (Packed Cell Volume)

To determine hematocrit, whole blood is centrifuged to pellet the red blood cells.

Plasma remains on the top of the red cells.

The fraction of blood that is packed is the hematocrit and is read as a percentage.

Hemoglobin hgb

Hemoglobin (Hgb)

Normal values are usually 1/3 of the hematocrit.

Each hemoglobin molecule has 4 heme units attached to globulins.

Abnormal heme groups, cannot carry oxygen.

Carboxyhemaglobin- Hgb has a higher affinity for CO than O2.

Bright red blood

Methemoglobin- The Fe molecule is oxidized to Fe+3.

Blood becomes brown.

Tylenol toxicity in cats.

Red blood cells

Red Blood Cells


Carry oxygen to the tissues

Oxygen must be carried at enough pressure to permit rapid diffusion of oxygen.

The RBC is a vehicle for hemoglobin which is the carrier molecule for oxygen.

The sigmoid shape of curve is a result of the cooperative binding from the 4 hemoglobin molecules.

Transport of oxygen in the blood

Transport of oxygen in the blood

97% of oxygen transported from lungs to the tissues is carried in chemical combination with hemoglobin in RBC’s.



Production or Maturation of a RBC.

Only occurs in the bone marrow of normal adult animals.

Occurs in the spleen and liver of the fetus.

Maturation time usually takes 5 days.

Regulated by erythropoietin (EPO) which is increased in the presence of hypoxia.

In most species, the kidney is the sensor organ and major site of EPO.

Red blood cells erythrocytes

Red Blood Cells (Erythrocytes)

No nucleus due to have to fold and squeeze through tight spaces.

Normocytes- cells look normal

Erythrocyte life span

Erythrocyte Life Span

Dog- 110 days

Cat- 70 days

Cow- 160 days

Horse- 145 days

Man- 120 days

Mouse- 30 days

Erythrocyte life span1

Erythrocyte Life Span

Stem Cell → Rubriblast → Prorubricyte → Rubricyte →Metarubricyte→ Reticulocyte → RBC

Metarubricyte- nucleated RBC releases in severe anemia.

No more mitotic division takes place after this stage.

One rubriblast may give rise to as many as 8-32 RBC’s.

Normal erythrocytes

Normal Erythrocytes

  • Morphologic features vary from species to species

    • Dogs: Biconcave disk shape with central pallor

    • Cats: Generally round with little central pallor.

    • Birds: Contain a nucleated RBC

Categories of erythrocyte characteristics

Categories of Erythrocyte Characteristics

  • 1. Cell arrangement on the blood film.

  • 2. Size

  • 3. Color

  • 4. Shape.

  • 5. Presence of structures on erythrocytes

Cell arrangement on blood film

Cell Arrangement on Blood Film

  • Rouleaux

    • Rouleaux formation is a group of erythrocytes in stacks. This can be a sign of increased fibrinogen or globulin concentration.

    • It can also be an artifact seen in blood that is held too long before preparing the blood slide or in blood that has been refrigerated.

Cell arrangement continued

Cell Arrangement Continued

  • Agglutination

    • Agglutination, which appears as rouleaux, occurs in immune-mediated disorders. An antibody coats the cell causing bridging or clumping.

    • If you add a drop of saline to a drop of blood rouleaux formation will disperse and agglutination will not

Erythrocytes aka rbc s


  • Terms:

    • Anisocytosis:

      • Variations in size

      • Can indicate anemia

    • Macrocytosis:

      • Larger than normal cell size

      • Liver disease or Vitamin B12 deficiency

    • Microcytosis:

      • Smaller than normal cell size

      • Iron deficiency

Erythrocytes aka rbc s


  • Mean Corpuscular Volume

    • Describes cells as normocytic, microcytic, or macrocytic. Calculates the average volume of rbc’s.

  • MCV=(Hematocrit x 10)/RBC count in millions

    • Normal: 66-77

    • (we will come back to this calculation again)



  • Polychromasia:

    • Polychromatic erythrocytes exhibit a bluish tint. The tint is due to a small amount nucleus retained in the cytoplasm. These are young cells and may appear as a reticulocyte

  • Hypochromasia:

    • is a decrease in color, due to a decreased staining intensity caused by insufficient hemoglobin within the cell.

    • Iron deficiency is the most common cause.

  • Hyperchromasia:

    • refers to cell that appears darker than normal cells. This gives the appearance that the cell is over saturated with hemoglobin. The erythrocyte has a fixed maximum capacity for hemoglobin and over saturation can NOT occur.

Erythrocytes aka rbc s


  • Mean Corpuscular Hemoglobin Concentration

    • describes cells as normochromatic or hypochromatic.

  • MCHC= (Hgb)/(Hct) x 100

  • Normal is 31-36%

  • (we will come back to this calculation again)





Hypochromasia continued

Hypochromasia continued

  • Hypochromatic should be differentiated from cells with the center “punched out”. A punched out appearance can be an artifact due to improper smear technique



  • True hyperchromasia does not exist.



  • Poikilocytosis

    • Poikilocytosis is a major deviation in the normal shape of the erythrocyte. The term poikilocytosis is an umbrella term that is used for any and all abnormally shaped erythrocytes and does not suggest a specific diagnosis

Schistocytes fragmented cells

Schistocytes (Fragmented Cells)

Also known as poikilocytes.

RBC’s with abnormal shape.

Formed as a result of shearing of the cell by fibrin strands. This occurs when red blood cells rapidly pass through microvasculature that is lined or meshed with strands.

They are observed in fragmentation hemolysis caused by DIC, vascular neoplasia, endocarditis, and possibly iron deficiency anemia.

Acanthocytes spur cells

Acanthocytes (Spur Cells)

  • The term acanthocyte is derived from the Greek word “acanthi” meaning “thorn” Acanthocytes are cells with five to ten irregular, blunt, finger-like projections.

  • The projections with vary in width, length and surface distribution. These cells are seen in animals with altered lipid metabolism such as cats with hepatic lipidosis or dogs with liver disease.

Acanthocytes continued

Acanthocytes Continued

Echinoctyes burr cell

Echinoctyes (Burr Cell)

  • Echinocytes have multiple, small, delicate regular shaped spines evenly distributed around the cell and are indistinguishable from artificially crenated cells.

Echinoctyes continued

Echinoctyes Continued

  • Echinocyte formation can be artificial, often seen with slow drying blood films or if the EDTA tube was underfilled. This artifact is then termed crenation.

  • Echinocytes have been associated with renal disease, lymphosarcoma and rattlesnake bites in dogs.

  • They can been seen after exercise in horses.



Identified as the presence of many irregular membrane projections involving most RBC’s.

It is usually an artifact due to slow drying of the blood film.

Commonly observed in pig blood but can be seen in any species.

Drepanocytes sickle cell

Drepanocytes (Sickle cell)

  • These cells are crescent shaped with pointed ends.

  • Drepanocytes are often seen in normal blood of deer and goats. It is thought to be a result of low oxygen tension.



Keratocyte helmet cells

Keratocyte (Helmet Cells)

  • Also called blister cells or bite cells. Keratocytes are associated with trauma especially cellular damage from contact with fibrin strands.



  • Cells with pseudovacuoles are called blister cells or pre-keratocytes.



Cells have a spheroid shape instead of the usual biconcave disk shape.

Have reduced cell membrane and are hypochromatic.

Seen most frequently in autoimmune hemolytic anemia (AIHA).

Usually seen in dogs.



  • The appearance of stomatocytes with their oval or rectangular central pallor has been compared to a smiling face, a fish mouth, and a coin slot.

  • Stomatocytes are associated with a hereditary condition but are also seen in liver disease, acute alcoholism (humans), and electrolyte imbalances.

Target cells and folded cells

Target Cells and Folded Cells

Two types of leptocytes observed mainly in dogs.

Represent cells with an increases membrane-to-volume ratio not specific to any disease.

The cell membrane is thin and flimsy.

Target cells bull s eye cells

Target Cells (Bull’s Eye Cells)

  • Also called codocytes

  • Thin, bell-shaped cells

  • Centrally stained area

  • May be seen as

    artifacts when smears

    made in high humidity

    or if blown dry.

    Can indicate liver disease or hemoglobinopathies.

Target cells

Target Cells



  • These are bowl shaped erythrocytes that form as a loss of membrane flexibility that does not allow the cell to return to a normal shape after passing through a capillary. They can occur due to lowed hemoglobin concentration or as an artifact.

Dacryocytes tear drop cells

Dacryocytes (tear drop cells)

  • These tear drop shaped cells are seen in myeloproliferative diseases. These cells, when produced as an artifact can be identified by the direction of their tail.

Erythrocytes aka rbc s

  • Dacryocytes produced as an artifact have their tails pointing in the same direction.

Nucleated red blood cells nrbc s

Nucleated Red Blood Cells (NRBC’s)

  • Nucleated red blood cells (NRBC) usually represent early release of immature red blood cells during anemia.

  • These are nuclear remnants seen in young erythrocytes during a response to anemia.

Basophilic stippling

Basophilic Stippling

Observed in RBC’s that contain abnormal aggregation of RNA.

Can be observed in cases of heavy metal poisoning with non-regenerative anemias or intense erythrogenesis in dogs, cats, and ruminants.

Howell jolly bodies

Howell-Jolly Bodies

Nuclear remnants observed in young erythrocytes.

Often observed in cats and horses.

Can be seen in regenerative anemic animals.

Also may be seen with splenic disease or in an animal with the spleen removed.

Heinz bodies

Heinz Bodies

Particles of denature hemoglobin protien.

They stain with new methylene blue and appear as colorless bumps with quick stain.

May be caused by oxidant drugs and chemicals. Also associated with onion toxicity in dogs!

Normal cat blood may have 2-3%.

Spleen recognizes as abnormal and starts to lyse the cells.

Heinz bodies1

Heinz Bodies



  • These are immature red blood cells that contain organelles (ribosomes) that are lost in the mature cell. Cats have two forms of reticulocytes.

    • The aggregate form contains large clumps of reticulum. They mature into the punctate form within 24 hours.

    • The punctate form, unique to cats, contains two to eight singular granules. Punctate reticulocytes circulate for 7-10 days before the all the ribosomes are lost.

Reticulocytes in the peripheral blood

Reticulocytes in the Peripheral Blood

Non-nucleated cell containing RNA which can be easily seen when stained with methylene blue.

Hallmark of erythrocyte regenerative response.

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