RBC - Morphology Flashcards
RBC
in most species have a round, bi-concave shape
Thinner in the middle than at the edge → central pallor
Erythrocyte Color
Young RBCs
Released early
usually larger and more blue/purple from RNA
Presence/absence of polychromatophils is important in determining if anemai is regenerative or nonregenerative
Horses are unique, they do typically no relaese polychromatophilic cells in the face of anemia
Rubricytosis
AKA, Nucleated red cells
Significance:
- regenerative anemia:
- appropriate rubricytosis
- Blood loss or hemolysis
- Nonregenerative anemia:
- inappropriate rubricytosis
- marrow damage - inflammation, necorsis, etc.
- Lead poisoning in dogs
- Extramedullary hematopoiesis, splenic contraction, splenectomy
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Anisocytosis (variation in sizes)
significance depends on reason for vairiation of size
Macrocytes
Microcytes: decreased volume, hypochromic
Spherocytes: normal volume, decrease amount of membrane
Erythrocyte size is best determined by measuring the MCV
Macrocyte
incomplete maturation or skipped cell division
- significance:
- usually means increased erythropoiesis
- release larger immature cells
- Increased MCV with anisocytosis due to macrocytosis is the best evidence of increased erythropoiesis and bone marrow response to anemia in equine CBC
- usually means increased erythropoiesis
Increased diameter, and Volume
Microcyte
increased cell divisions during development and decreased volume
- Potential causes:
- iron deficiency
- hepatic unsufficiency
- Greed vairation
Spherocyte
lack of central pallor together with the apparent hyperchromasia are characteristic
Changes in Central Pallor
Poikilocytosis
Variation in shape
significance depends on shape
Echinocyte
often regularly spaces projections
Artifact - cell dehydration
envenomation
Other diseases but not consistently
Acanthocytes
Irregularly spaced projections
altered lipid metabolism
Liver disease in cats
Hemangiosarcoma in dogs
Shistocytes
RBC that is lysed by a fibrin strand in the artery/vein. The lysed fragment is the shistocyte
Codocytes
Target Cells
Central focus of Hgb surrounded by ring of pallor
Formation: excess membrane relative to amount of Hgb
Heinz bodies
indicative oxidative damage
Large, membrane bound affrefates of denatured hemoglobin
Eccentrocytes
fused, unstained, cresent-shaped region of membrane, with a shift of hemoglobin to the opposite side
Hallmark of severe oxidative damage
pyknocytes
Not sperocytes
different pathophysiology
Loss of fused membrane portion of eccentrocyte
Basophilic Stippling
Formation: ribosomal RNA not degraded
Signifinance: Regenerative anemia
Lead poisoning
Howell-Jolly bodies
Nuclear remnant
Significance: low numbers in health
Regenerative anemia
Most important thing is to not call these parasites
Rouleaux
1 drop blood + 9 drops saline
Charge attraction - nonspecific sign on inflammation
Except in horses, where this is normal
Agglutination
1 drop blood + 9 drops saline
Antibody-related cell bridging
Used to diagnose Immune Mediated hemolytic Anemia
RBC Physiology:
Function
primary function of RBC is to carry O2 from the lungs to the tissue.
RBCs also transport CO2 from the tissue to the lungs and buffer H+
RBC physiology:
Flexibility
in part due to the flexible membrane and shedding of the nucleus
RBC physiology:
Strength
stong but flexible membrane able to withstand recurrent shear forces involved in blood circulation
RBC physiology
Shape
biconcavity allows for increased surface are for gas exchange
RBC physiology
Hemoglobin content
unique to the RBC, hemoglobin is pivotal to the development and oxygen transport ability due to its affinity for oxygen
RBC physiology:
Lifespan
because the mature RBC has no nucleus, the cell cannot divide or repair itself. The lifespan is therefore relatively short and varies between species
RBC deformability, structure, and Strength
Ability to change shape in response to stress and to recover once the stress is removed
- Deformity is dependent on:
- structure of the membrane and cytoskeleton
- High surface area to volume ratio
- Low viscosity cytoplasm
Alterations in the lipid or protein composition of the membrane may result in abnormal red-cell shape
Deformability allows RBCs to move through the circulation without loss of structural integrity and is a major determinant of blood viscosity
Erythropoeiesis
Is a complex process that occurs in the bone marrow. before a RBC arrives in the blood stream, it must develop from a stem cell and progress through a number of stages
Most effective in bone marrow
Tissue oxygenation is the main regulator
renal peritubular interstitial cells produce erythropoietin in response to renal hypoxia
anemia
poor oxyfenation of blood
poor renal perfusion
High erythropoeitin
erythroid hyperplasia
shortened erythroid maturation time
increased hemoglobin synthesis in dividing cells
Decreased apoptosis of progenitor cells in the bone marrow
Accelerated release of reticulocytes from marrow
Erythoproietin low
RBC production < RBC loss
Gradual onset of anemia
Causes: decreased function of renal tissue, and inflammation
